which came first?

You are forgetting the third possibility: advocates.  It doesn't matter
_what_ is advocated - no more than for any other tosser.  S/h/it might
change the poster when it's sufficiently covered with, er, drying evidence
of affection and the next one might even have a different picture on it.
If you hold your nose and look into old usenet archives, you'll see any
number of those migrating from one "community" to another - Amiga to OS/2 to
MacOS to BeOS to whatnot, with the same kind of rethorics and the same
whatever it is that replaces mind in fanboys.  VMS ones too, if you go a bit
earlier.  They migrate; it had been rather amusing in a sick kind of way
to watch exhalted Linux advocates go and pester FreeBSD folks in a more
embarrassing capacity - that of equally exhalted FreeBSD advocates.  BTW,
they seem to have a territorial behaviour of sorts; ones who discover the
new territory appear to emit satisfied noises in direction of their slower
brethren.  Ironically, it resembles earlier behaviour of locals, who used
to enjoy relatively idiot-free environment and to taunt the previous victims
of advocates' attention by associating those with the flocks of turd-flinging
pests.

The choice of enemy also can change.  FWIW, it looks like the real attraction
for persons in question is a safe and heroic fantasy - that of bravely
fighting the terrible enemy of humanity and feeling themselves comfortably
exempt from any kind of work that might require intellectual efforts.
IOW, Luke Skywalker wannabes.  It's not about being anti-MS or pro-Linux, etc.
What really counts is seeing a setup that might match their template.

I'm not a prude and I certainly do not deny that they are entitled to their
kinks of choice, but there's a difference between being hostile to people
fond of buggering dead chipmunks and being annoyed by vigorous demonstrations
of the same in public places...