A lot of it's that unfortunate by-product of mtbing's increasing popularity. In most cases these incidents come down to a lack of understanding & awareness of trail etiquette (or the implications for lapses in commonsense despite the obviousness of the outcomes) for these relative new-comers to the sport, who in a sea of marketing, misconceptions & gung-ho naivety get themselves & other riders into all sorts of trouble. Conversely I also think there's plenty of occasions where the more seasoned of us, who've been around the block for years, can be quite intolerant of these newbs & rather than taking some time to politely explain the error in the ways of said dickheads being stopped in the middle of a blind corner/transition/ having a group pow-wow on the trail, instead the seasoned guys can go off the handle or be completely dismissive & shunty towards them.
I mean there's no two ways about it, in the case of riders climbing up clearly marked & signed descending trail or blatantly endangering other riders & trail users then, yeah, that idiocy deserves a pretty stern dressing down & any lipiness from the offender is liable to result in a homemade facelift, but I'd like to think that level of incident on the trail is reasonably isolated.
At the risk of sounding like I'm suggesting this thread be amalgamated with the "Grumpy Old Man" thread, I think one of the big things for the riders who've been around a while is the fact that vehicles like Farkin/Rotorburn were thriving digital hubs of dialogue & people formed & rode with like-minded crews of riders, & everyone did a good job of keeping each other in check. MTBing was community. You generally didn't have a great number of riders who just 'dabbled' in mtbing- you either did or you didn't. You were either a MTBER or you weren't; we sought information, connected & banded together though shin scabs & stories of glorious stupidity. In exactly the way surfing has evolved (as a recreation/sport/culture/technology), as mtbing has become a more popular sport & the abundance of accessible trail info being located at the click of a button, so too has our culture evolved, & it has brought with it a whole population of recreational dabblers/"part-timers" to our trails who are coming into the sport from a completely different angle to most of us. Much like the ever changing face of surfing's floundering kook, dropping in on you or cluttering the lineup while they flounder on their board, mtbing's going through exactly the same thing. And those of us for whom mtbing is an integral part of their being/life-force/purpose etc.,we're going to have to get used to it. I'd be appalled if mtbing developed an entrenched culture where a "locals-only-esque" mentality or attitude was present.
Lord knows letting fly with the intent of hurting someone should always be the last option resorted to so hopefully GDonohue's situation is one of those incredibly rare incidents. It is apparent that there's a sense of remorse over it unfolding the way it did, & I'd be lying if I said I hadn't actively pulled up or chased down guys who I deemed to "have ought to know better" for a dressing down on trail behaviour, but it's safe to say that there will always be an exceptional category of fuckwit such a Brad or Kenny "The Warrior" Kookton. Both will always require being put in there place- be it because they're being a stationary trail liability or because they're being complete Stravaholes. As too will there be always be a need to remind ourselves that we all started out somewhere & benefited from a bit of helpful advice along the way- even when we might've figured we knew shit about mtbing.
Fundamentally so long as we're all adopting a "Be a dude. Don't be a dick." attitude to our mtbing then as a lifestyle we all ultimately benefit from it- people do less dumb shit out on the trail & we more-often-than-not get home safely & have had a good time.
But yes, I f#@ing hate people who do dumb shit on trails.