https://kotaku.com/superhot-game-gets-review-bombed-after-removing-depicti-1847352470
This was in direct response to changes in the game, any negative reviews because of changes made to the game are legitimate reviews, not a 'review bomb'.
triggering Valve’s anti-review-bombing tech to kick in and filter out the flood of bad-faith evaluations.
https://kotaku.com/valve-says-it-will-remove-off-topic-review-bombs-from-s-1833332643
“We’re going to identify off-topic review bombs, and remove them from the Review Score.”
Of course Steam is the arbiter of what they deem 'off-topic'
Your claim was that it never happened, this was just a single well known example of it happening.
Also it isn't fully automatic. Valve claims that people are involved 'evaluating it', and the result of the evaluation was that reviews were not counted.