Well I don't usually need to connect audio from Firefox directly into a DAW or synthesizer. And technically that could still be done with Jack, it's just a bit harder to do because you have to create additional pulseaudio sinks first.
But I don't recommend using only ALSA without a sound server on a desktop, the usability of it is pretty bad.
I have found ALSA useable, over many years. But I've never understood the config notation, so my configs have always been pretty cargo-cultish.