It could be that in most cases gas engines are used on "giant scale" or at least larger than your typical electric or glow airframe. The amount of participation from this demographic has, for the most part, long left RCU. Just go to the Giant Scale forum and look at the number of participants and the level of expertise of those who do participate.

Other sites, whose links would be censored if I typed them here, have stepped up and filled in the gap.