> If AMD and Intel can dedicate resources to maintain their Wayland implementations with no complains why NVidia can't?

nVidia shares the driver with Windows, AMD/Intel don't. So AMD/Intel always give you a driver that's significantly trailing the Windows versions on features and stability (you can read a lot about this on Dolphin blog for example) while adding more maintenance costs.

> Because they could use the time spent on maintaining NVidia proprietary API adapter writing open-source software that will benefit all parties.

What do you mean "all parties"? They're excluding at least one party - nVidia users.