I think that might be a fair evaluation about 5, 10 years ago. But now we have a *NIX OS, and a horde of propeller heads to go with it. Not to mention some of us Mac geeks that have evolved to be *NIX geeks.
I've been a Unix sysadmin for 20 years. I've been using an OS X desktop for the last 5 for several reasons:
o Sun stopped being even remotely competitive bang/buck on desktop systems
o I tired of the effort required to maintain desktop-y tools for Solaris, as the stuff Sun ships tends to be old, bloated, and poorly-chosen
o ... so I want my desktop these days to Just Work. OS X gives me that, but on a Unix platform with a real shell that lets me do what I need to do.