I'm not claiming the anti-aca crowd are "right," and I think some of them are dead wrong. (The idea that essays on other people's journals will spoil their fan-fun... umm. No, not following that one.) However, part of the complaints are "I don't like doing all that heavy thinky-stuff"--so of course, they're not going to be neatly charted into bullet-points that can be argued in the academic style.
However, I do not that there is no discussion... there is "I'm right" and there is "no, you're wrong; I'm right" and there's a storm of "Yeah, what SHE said!!!" on both sides.
If I were going to play squeefan advocate, I might be able to come up with a few things:
* Detailed analysis of subject matter that was never created with that kind of scrutiny in mind, misses the point (not my problem) and can ruin the fun of people who run across the scrutiny (limited-range problem).
* Entire communities (and by that, I don't mean LJ comms) that demand that kind of attention to detail to be a respected member, creates an atmosphere of exclusion.
* Insisting on one particular approach to fandom as the "correct" or "most intelligent" one, makes fans who don't have that approach more likely to go away and do something else--and that is bad for fandom. (Unless there's a consensus that acafandom is *the* way to be, and it's okay to drive off/ intimidate anyone who doesn't agree, and I hadn't seen acafen insisting on that.)
* Using the same tone, vehemence and other patterns of communication to argue against racism and bad SPAG sends the meta-message that these two are equivalent sins. This can lessen the impact of important social-issue messages as "just more wank." (And indeed, this issue gets thrown around every time a big social issue makes Metafandom: is it fair to call it "wank" when it's people's lives & livelihoods being discussed?)
* The concept, "we are better than them because we are well-educated/we like well-educated discussions" smacks of classism. I'm not sure how directly that connects to the acafandom discussions; many strong aca-promoters are not "upper class." (However, I don't know of any "upper class" fans who dislike acafandom.) (Definitions of "upper class" or "lower class" may need to be an entirely separate debate somewhere else.)
Those aren't solid, and I'm not arguing firmly for them. Just some examples of the possible points of contention.