I don't think you realize the depth of Adobe creative suite hate, an entire generation of artists came up on Krita/Affinity because Adobe decided to vampire its customers.
It's deep with a small number of very loud people.
...which is one of the benefits of it being open-sourced with a permissive license. If it stops being maintained, it can just be forked.
The "no one maintains AI slop" idiom is more for things which are bespoke and/or don't have much demand, and this clearly has demand.
Why would anyone help maintain this when they could vibe code their own though? Genuine question. As of the time I'm writing this there are already two other people linking their own Adobe clones in this comment section.
It takes a lot of tokens to vibecode something like this with the expected feature sets, and this domain is complex enough with enough edge cases and interactions such that it's infeasible to fully QA even programmatically.
Why ? Obviously it was possible to write Photoshop itself with human QA, and human QA is fundamentally limited ... and is more limited than programmatic QA. At the very least this repo will start to catch up fast with Photoshop, assuming it's maintained.