Note that this table is written by one of the musl authors; not that there's anything shady about it, but it's a list of what the musl authors think are important, so it's to be expected that musl is trying to check off all the boxes, wheras other libc implementations may have different goals.
Yes. If anyone has suggestions for other comparison points I should add that would be more balanced, I can try to add them (but some things require non-trivial work to measure so it might take me a while to get around to it). Note that the comparison table as it stands it pretty old, but very little has changed since I did it except musl getting slightly bigger and glibc getting a lot bigger (and eglibc merging back into glibc, so it's rather pointless to talk about it as "eglibc" anymore). :-)
Musl is fairly new, and it's linux-specific, for those reasons I think many have not heard of it.
But it is very good. We use big parts of it in emscripten for example, and it works great - nice new and compact code, permissive MIT license, friendly upstream.
Why have I not heard of it until now?