Yeah, for sure, but without easy way to access it from the keyboard, most don't bother wasting time inserting it.
Smart tools like LibreOffice and above indeed help with it, but in other scenarios, especially common browser usage that's not the case. Compose key is really useful for that, but it's not widely known outside of Linux.
This dates back to the beginning of the Mac, so it's almost 10 years older than FreeBSD. (I'm unfamiliar with other UNIX compose key tooling that may have predated it.)
Smart tools like LibreOffice and above indeed help with it, but in other scenarios, especially common browser usage that's not the case. Compose key is really useful for that, but it's not widely known outside of Linux.