Not supporting Nvidia cards will make Wayland unusable for at least half the Linux desktop users, probably more. Stats I recall range from 50-75%.
“Just buy non-Nvidia” is not, I repeat, a simple option. Lots of people stick with old GPU models because the price/performance ratio has gone out the window and they cannot afford to drop hundreds or thousands on one. Many others have Nvidia in their laptops.
There’s nothing preventing Wayland from working with Nvidia except the political insistence that it be open sourced. Which Nvidia is not interested in, never was, and never will be. And it’s a red herring to begin with.
TLDR either Wayland bends their stance on open source or their adoption will be severely limited.