Sway is a WM, and wlroots is a new library that should help in creating Wayland WMs (similar to wlc). SirCmpwn has to maintain all of that, and it turns out it's a fairly big task. Realistically, his WM will run on hardware running Intel for the most part, with AMD or Nvidia way behind. Optimizing for Intel is fairly simple, and it turns out it gives AMD support for free, since they use the agreed-upon APIs. His choice makes sense.
The thing is, people are going to always ask why that choice have been made. And I can understand this being super-frustrating, hence the post being so harsh on nvidia. But really, nvidia deserves it. Wayland wasn't designed in a vacuum, and nvidia took the wait and see approach. Once every bit were put in place, Nvidia came up with the EGLStream proposal. Not during discussion. After everything was said and done. Adding a codepath for EGLStream is really non-trivial, and I hope nobody does it because it really adds additional complexity.
Really, that AMD is getting more competitive is going to help the GPU world a lot. Nvidia has always been a bad citizen there, and oh boy if AMD ever gets in a position where they can compete on compute, that'd be great.