> this "thing" that true skaters share, can the posers take that away? If not, why the ire?
No, unless someone's feeling strangely insecure about his own self. That's why I draw no ire per se: The only thing that enrages me is more of a side effect of some posers being dicks (mostly because they think sk8rs are deh bad4ss dop3 sh1t and making an attitude display of it), and other people hating skaters because of the shitty attitude of people that look like skaters to them.
Honestly I just compassionately find it quite sad that someone would rather pose as something instead of, well, being (or striving to) that something. The latter is so much more rewarding, whatever it is. Also, there's a failure of genuineness that I find intellectually bothersome. You could basically have the same argument about anything, like l33t h4x0r kiddies vs public perception of the "hacker" word vs the meaning of hackerdom (as in http://www.catb.org/jargon/).
> also rather hostile towards wrongboarders, inline-skaters, parkour-runners and any other street-based activity except BMX (they're cool somehow). It's all very tribal and I really can't relate.
In decreasing order of hatefulness we hate scooters (because it's lie a skateboard, with a handlebar. hah, trainers.), parkour-runners (because they just use their feet. gross.), inline-skaters (because the wheels are merely tied to the feet, how lame is that?), and longboarders (because they didn't bother to learn to ollie). BMX get a pass because they slam their nuts on a bar similarly to how we do on a rail (but hey they have a handle too, so...) Buuuuut really that's all in jest, nobody's serious about it and we definitely try each other hardware from time to time, having fun at how "easy" each other's sport is and laughing our ass off at how much we suck at it.