There is too much them and us in light aviation, period.
I currently fly old GA, modern GA, and flexwing microlights - in the past I've done a lot of 3-axis microlight flying, and a bit of gliding.
I've had GA airfields turn me down because I was flying a microlight, modern GA pilots decline a go in an old taildragger as irrelevant, had a very hostile reception for turning up powered at a gliding club (despite PPR, etc.), and seen a microlight pilot drummed out of a microlight airfield because he'd dared to get an NPPL and buy a light aeroplane.
It's clearly commonplace because numerous occasions where a glider has diverted into my favourite microlight club, and I've gone up with my customary greeting of "welcome to XXXX, kettle's on, can I help with anything apart from pushing your glider off the runway", the first thing I usually see on the pilot's face is relief.
And we should not tolerate it. In our own clubs we should stamp firmly on anybody who shows this sort of behaviour - welcome everybody, whatever they fly. Help them fit in, and when they screw up an break local rules, be nice about it, just make sure they know what they did and how not to do it again.
Equally, turn up somewhere different, and there's a moral imperative to understand that environment and fit in. We can all make the effort to do that.
G