BeOS was also a single-user OS, which made it a nonstarter for businesses. It wouldn't fit within corporate IT as it existed at the time. NeXT, however, and Mac OS X based in large part on it were both multi-user OSes which could actually be used by businesses more reasonably.

And I'm using "business" in a generic sense. This was an important quality for schools, as well, where Macs were incredibly popular (for a number of reasons, including favorable pricing from Apple and historical support for schools since the 80s). Single user OSes just don't fit within any organization trying to at least pretend to have decent IT.