The Platonic ideal of the isolated and singular cartoonist is an enduring image - Charles Schulz at his drawing board, toiling for fifty uninterrupted years. Certainly, there can be no doubt that the majority of truly great works in the field have been the product of singular minds. But it would be unnecessarily reductive - not to mention erroneous - to dismiss the smaller but still substantial body of work created by cartoonists in tandem, or by writer / artist teams. This is the exact attitude adopted by many in thrall of the conception of the "cartoonist as auteur" - mostly cartoonists themselves, it bears adding.
The backlash against commercial compromise is a faulty foundation on which to build a working model of art. Comics encompass such an incredibly wide and varied field of work that it is only the height of pique to imagine any particular style or production method as being any more or any less comics. Perhaps some artists can legitimately make a claim to cartoonist as a specifically individual calling -- Ivan Brunetti did as much in his recent Journal interview -- but even then we're on shaky rhetorical ground, the kind used as a roundabout way of denigrating "illustrators" or "draftsmen".
Judging art as a political extension of the means of production has always resulted in exclusionary didacticism to the detriment of aesthetics. To announce, blanketly, that art cannot be made by committee is to invite a thousand dissents from defenders of the Hollywood studio system or jazz or architecture or Homer or the Bible. But similarly, to dismiss the effect of commerce on art as trivial is to misunderstand the ability of commerce to warp the critical - and artistic - vocabulary. Anyone who knows anything about the history of punk music can see how the constant paranoia against the Bogeyman of "selling out" can limit horizons and stifle possibility. If I had to listen to nothing but bands on the Dischord label for the rest of my life, it would be a pretty boring life.
Historically, the prevalence of assembly-line comic books and strips in the American mainstream was the source of much of the alternative world's identity. Just fact that they were designated as the "alternative" or the "underground" for so long implies that they were conceived in a disadvantaged relationship to another way of being - born under a proverbial bad sign. Maybe this was true at one point, but it need not be true any more – and there is no good reason why these attitudes need to be advanced to the next generation, not when there are for more important values to transmit.
It's easy to see that there are economic factors at work here. Most American alternative comics don't pay very well, and consequently most of the popular artists are driven by obsessions more powerful than money - as threadbare as Chester Brown looks now, imagine if he had to pay someone else to draw his comics for him. As rare as that kind of dogged obsession is in an individual artist, imagine how rare to find two people sharing the exact same obsession, to the point of devoting their entire lives to the execution of said obsession? I don't believe for a second that if two young artists or an established writer / artist team banded together and decided to create the next masterpiece of comic art, they would have any trouble getting it published almost anywhere they wanted. But the economics just aren't there yet, at least not in America - or we'd see it happening all over the place.
The most influential generation of living cartoonists is the post-underground generation that came of age, artistically speaking, in the 1980s. The cartoonists of the underground didn't feel the need to contrast themselves so inexorably against the mainstream - they were doing something entirely different. They weren't economically beholden to a limited direct-market system for their distribution, and they weren't in competition with Superman for their rent money. But the first generations of Fantagraphics and Drawn & Quarterly cartoonists were by and large dependent on the direct market for distribution (although this only got worse as the 80s turned into the 90s and the market contracted), and they were in direct competition with piles of crappy superhero comics. It's easy to see the resentment in the work of artists like Chris Ware, Chester Brown, Seth, Dan Clowes and Charles Burns. The passive-aggressive relationship of these artists to the crappy superhero comics of their youth is absolutely essential to understanding major portions of each of their bodies of work. The fact that Los Bros Hernandez have escaped this passive-aggressive relationship, and have each even accepted checks from DC Comics at times, betrays the fact that both Jaime and Gilbert's attitudes would be far more at home one generation removed from their closest peers.
Although I've spoken many times about limiting the influence of cinematic metaphors on our understanding of the medium, the movies do offer a wonderful framework with which to shape our understanding of the question of collaboration. Cinema is by its very nature a collaborative form - it is almost impossible to create a movie without help, and any movie created in such a singular vein would be pretty solipsistic, having only one actor, one writer, one cameraperson, editor, cinematographer, costumer, musician, etc (which isn't to say that it hasn't been done, because I'm sure it has). Even the most rigorous auteur to ever walk a soundstage was still dependent on dozens or hundreds of underlings to cooperate on the execution of a singular vision that became, by dint of said execution, a plural vision. By contrast, writing is almost always a singular act. Collaboration is not unheard of but it is rare -- look at the inherent novelty of something like Harlan Ellison's Dangerous Visions series. It also goes without saying that anyone who works in "serious" literature goes it alone automatically.
Comics are neither cinema nor literature, but instead take parts of both, in addition to multiple other disciplines, in order to create something different. Similarly, comics can be created in the modes of cinema or literature -- with either multiple creators cooperating to craft a singular vision or a singular artist working in isolation. There is no objective standard that places the product of the one method above that of the other. The only real standard is that of the work itself: is it any good? The fact that truly compelling works of collaboration in the North American branch of the medium are relatively rare only makes them more precious. Hopefully, as comics expand outwards from their ghetto, the prejudices on the part of solo cartoonists, as well as the stifling economic factors that force them to toil in isolation and obscurity, will at least partially dissolve.