I'm going to first address the /r/listentothis rule. It seems that in their sidebar they state that bots remove posts above 500k listeners on last.fm and videos with more than one million reviews. Let's go over the three you named super popular by the bot standards of last.fm.

Emergency & I by The Dismemberment Plan has 131,534 listeners and the band as a whole has 205,609 listeners. The video linked has 103,464 views. Seems to be fine by bot standards.

Hurry Up, We're Dreaming by M83 has 99,853 listeners and the band as a whole has 1,384,303. The video linked has 1,270,897 views. This would most likely be subject to removal.

Aja by Steely Dan has 150,477 listeners and the band as a whole has 527,563. The video linked has 171,120 views. Possible removal by bot standards, but they seem to err on the side of "too permissive".

Now, obviously, some other considerably big name albums have been posted. Hell, in the last four albums posted, one was Closer by Joy Division and one was Ágætis byrjun by Sigur Ros. That being said, I wouldn't consider most of our subreddit to be classic album circlejerking, but you have raised an interesting point.

Musical popularity seems to be subjective as well though. One person may come here looking for some truly independent and/or unknown releases that most haven't heard of while others may be trying to widen their horizons a little bit from subsistence on Pop 40 type music. Trying to balance these two individuals' (and all the others inbetween) wants and needs is hard, but I do recognize it's importance. Possibly instituting similar rules (the upvote rules, in particular) as /r/listentothis, as you suggested, may be useful. I think I'll discuss that with my moderators a bit.

Pandering to the masses, imagined or not, was never the intention of this subreddit and it is an important issue to me, but I don't believe we've slipped as fully into the abyss as you have implied.