I’m sympathetic to your POV but the reason you should is that’s the price to keep things open.
Obviously many people don’t care about that. Fair enough. But then you should be prepared to deal with their shenanigans.
Prusa also does things like maintain and develop printables.com and PrusaSlicer (itself forked) which many of these closed printers fork with minimal changes.
People don’t care about this either. So again, get ready to deal with garbage when Prusa goes under.
I think it’s sad since the whole domestic 3D printer thing started as open source.
No, it's not, and the perception that it is hurts the cause of openness.
Open Source has every ability to be better, to Just Work, to not require constant debugging. Good Open Source systems manage this. The fact that 3D printers apparently have not is the fault of those printers, not any inherent quality of openness.