I certainly agree with you on the hourbuilding issue. In fact I can never understand why so many prospective ATPLs needing lots of hours insist on hourbuilding in rental aeroplanes rather than buying something like a VP1 or minimax and flying the pants off it.
£2-3k in microlights will get you something like a Goldwing, which is a 65mph cruise single seater at around 2 gal/hr, or any of a whole range of 2-seat flexwings that will cruise at 40-50mph at around 3 gal/hr. I run both, and around £20/hr all in is pretty close to the mark on both. So, I maintain my point that down in the weeds, microlights and group A are much the same.
Like you, I certainly don't understand the "them and us" that exists between two very similar branches of aviation, or even more so between either branch and gliding. All very silly and unhelpful.
G