I think their main problem is that regarding the i3 design, they are pretty much the only-ones contributing to improvements, I mean - when was the last time the community (or another manufacturer) actually contributed anything useful to the core HW and electronics design? The 3d printing space has massively changed in the last 10 years, where initially a lot of the HW improvements came from the hobbyist RepRap community. Now they come from a single company which stems from that community, and which is spending money on R&D.
On top of that, people still building an i3-design printer from scratch is rare, the hobbyist design community has moved on to the Vorons, which means pretty much all printers with this design are from companies with zero community interaction, profiting from the Prusa investments. So I get why they're not happy.
The only real comparison you have with Prusa is the much less popular RatRig - which is still an opensource design afaik, but I'm not aware of any clones of those.
On top of that, people still building an i3-design printer from scratch is rare, the hobbyist design community has moved on to the Vorons, which means pretty much all printers with this design are from companies with zero community interaction, profiting from the Prusa investments. So I get why they're not happy.
The only real comparison you have with Prusa is the much less popular RatRig - which is still an opensource design afaik, but I'm not aware of any clones of those.