They want lock-in for their UI/X, presumably. If Photoshop ran in the cloud, I doubt Adobe would let you make an alternative front-end either. Not that I'm sympathetic to them.
We'll know for sure when they add full OpenClaw-like features to Claude Code like remote channels & heartbeat support. Both are partially implemented already.
Off topic, but there is something like that: photopea, it's free and it's good enough for my use cases (I need it once a year maybe).
Saying Photopea is good enough is really underselling it. It's so far ahead of anything offered by the open-source community.
I'd be so happy to pay for a fully offline version of Photopea!