Most arguments tend to get started/encouraged by people exactly as you've described yourself, only ever read about DIR yet somehow has managed to inherit everyone else's knowledge whilst having no experience to back that up with. Or as the great Scottish term goes, a chanty wrastler (noun:
someone who makes noise by slopping a half full bucket of piss around).
The arguments may well be new to you but speaking for myself I've been hearing them since 1995. In the grand scheme of things i.e. actually diving, no-one gives a toss. The hostility is more a feeling of futility that the same old shite is dragged up again.
I've been diving with backplate, harness, long hose, ally stages, etc., since about 94/95 and I've never yet had anyone comment negatively on that (though I'd never qualify as DIR). I think a lot of people invent the whole hostility thing to try and lend a bit of cred to what they do.
Bloody hell, I'm defending DIR. I feel unwell
Cheers,
Stuart