Alacritty is already pretty performant (relative to a lot of the other terminal emulators), but my read is Ghostty has been going hard over performance/standards/protocols (like Kitty).
I did consider that. I remember nope-ing out of alacritty in the early days after seeing the developers response to people requesting a scrollback buffer. It amounted to something like "I use tmux, and if you don't, you use the terminal wrong." It left a bad taste in my mouth.
Ligatures are a renderer issue, so using alacritty as a lib wouldn't have this issue (it does demonstrate their hardline stance). Another example that would translate is how long it took them to support disambiguation of key combinations: https://github.com/alacritty/alacritty/issues/6378 (2019-2023). Of course, the maintainers are free to do whatever they want with the project - but such things do make alacritty-as-a-lib an exceptionally bad choice for situations where you want things to just work.
