All versions of MUSL prior to 1.2.4 (released less than two years ago) would indeed fail to perform DNS lookups in many common cases, and a lot of programs could not run in MUSL as a result. (I'm not aware of what specific deficiencies remain in MUSL, but given the history even when there are explicit standards, I am confident that there are more.) This wasn't related to dynamic linking though.

Glibc's NSS is mostly relevant for LANs. Which is a lot of corporate and home networks.