I will read the article later, when I have more time, but many geeks that only know Linux and eventually BSD, have no idea how painful commercial UNIX systems can be.
Several of our customers have HP-UX systems that look like plain System V systems straight out of the 70's.
That was my first response to Linux when I was first trying it out. Back in the mid 1990s.
At the userland level especially, it didn't suck, and (with the GNU userland, windowmanagers, etc.), in fact, sucked radically less than stock commercial Unices I'd been using at the time (Sun, HP, AT&T, Data General, BSD).
The situation's only gotten much, much better.
I'll occasionally find myself in situations where I'm connecting to commercial Unix boxes (was a semi-recent shop where a fair number of staff still ran CDE desktops), and, really, it's painful. Doable, but painful.
Sure HP/UX and friends always were terrible, but in 1995 I actually failed in love with Unix thanks to IRIX. IRIX really had a nice UI, easy to use management interfaces, powerful multimedia capabilities. Only installing anew it was bringing me back to the stone age (particularly the partitioning part, "inst" package manager was actually decent).
Commercial systems operate under constraints that Linux didn't have until recently, such as needing to maintain backwards compatibility. This went all the way from not changing the interface for people who used workstations for highly skilled works but were not "geeks" (e.g. CAD guys), to sticking with old shells (e.g. Sun stuck with ksh long after Linux had bash). Witness the furore over the GNOME team changing things a couple of weeks ago...
Several of our customers have HP-UX systems that look like plain System V systems straight out of the 70's.