I think your last sentence is getting close to the truth. You're no longer the audience for those descriptions. Other robots are.
I'm not saying that's good or bad because I don't know, but I think that's the idea of dumping all that junk into PR descriptions.
However, annoyingly, we still need to review those descriptions very closely, because the robots are trained to put a lot of weight into things they read in the documentation. And they tend tospresent loose speculation as fact. They often end up documenting some assumption that isn't true, then end up writing code as if it were.
Even worse, in a brownfield codebase that was once fairly light with comments, that's now being subject to these modifications, the insane amounts of commentary around the parts newly touched by AI lead to an excessive emphasis on those parts, for both human and AI readers (who think, well if this one part is commented so thoroughly, it must be unusually subtle)