Selecting releases for an Aoty poll requires you to go through everything you've listened to and to reevaluate the music. Now, if you did that regularly and adjusted your ratings, that would have a similar effect on the rating based lists. But most of us are not doing this. And not everyone likes to assign ratings to releases in the first place, and even with a fine-grained approach like at AP (where you have 100 steps as opposed to the 5 stars at PA) you cannot do the ranking quite as well as with just arranging releases in a list. So most ratings in music databases represent an user's opinion about a release at one point in time, usually at a time when they were still getting used to the album.

TL;DR: Ratings and ranked lists both have their place, both are useful, but offer slightly different perspectives on the music. Ultimately I think that continuous Aoty polls are more valuable than ratings. Case in point: Check out https://rateyourmusic.com/release/album/radiohead/ok-computer/" rel="nofollow - Radiohead's Ok Computer at RYM - it has recently broken 100k ratings. What does that mean? Not as much as it being on a lot of "top releases" lists.