It's rather nvidia proprietary driver that doesn't support standard Wayland protocols and thus doesn't work with Sway not the other way around.
See this for details: https://drewdevault.com/2017/10/26/Fuck-you-nvidia.html
Also, porting proprietary drivers for Linux must be a pain because there is no driver API and you cannot just release a closed-source driver and forget about it, you have to open source it and maintain it forever. No wonder manufacturers don't want to bother with this.
If you're NVidia user you're justified to feel bad about this entire fiasco but remember protocols exist so that everyone implements their own part and users can mix-and-match and it works together.
If AMD and Intel can dedicate resources to maintain their Wayland implementations with no complains why NVidia can't?
> why Wayland developers don't want to write an adapter for NVidia's proprietary API
Because they could use the time spent on maintaining NVidia proprietary API adapter writing open-source software that will benefit all parties.
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.
"They" being Nvidia here. AMDs amdgpu driver clearly shows the problem is neither Linux nor Wayland or Sway.
I mean all parties that implement the standard protocol. It's rather nVidia that's not interested in giving their users a chance to use properly Wayland not Sway developers "excluding users" by not doing free work for nVidia.
Please elaborate more. I'm writing this from my Dell XPS 9575 with Vega M GL under Fedora 30 and I haven't encountered a single problem in GPU-accelerated applications and games with official open source drivers.