I know I’m late to the party but I just found out and didn’t find a post regarding this
TL;DR: Steam now calculates review scores based on reviews made on your languages only (if enough). This is on by default, but can be reverted to go back to review scores based on all reviews (from people that purchased the game directly on Steam only)
Why do you think the scores are useless? They are good starting point and/or a way to evaluate smaller indie titles that often don’t get professional reviews.
I just haven’t seen any correlation with game quality. A short subjective rant from a random gamer is much more useful, especially with those hidden indie gems.