Self-sorting meaning that it has become "rude" to review an album professionally - unless you're Pitchfork or some other place with a high amount of industry clout - if you aren't already a fan of the genre or even the band in question. Obviously you don't want outright non-fans of a style to be reviewing albums in it, but I feel like rock criticism in the 70s/80s/90s was done more thoughtfully and from a more even playing field.
Which might play into what you were saying above - if a fan is doing a review and they don't like an album by a particular band, then it might be worth checking out, since it may mean that the band in question is trying something that they don't normally do.
This type of grade inflation happens also, IMO, because nobody really gives a shit about professional reviews any more. Reviewers aren't tastemakers. So a reviewer who gives out too many bad or mediocre reviews... that's guy is just a buzzkill. It's better for the publication to find people who are going to give out higher reviews.