With the wrong group? It's my farkin' club!* Actually, I was one of the 5 founders .... so not mine really, but I feel I have some ownership
I think it mostly comes from those who have been in one of the newer 'racing-style' clubs and are relative newcomers to cycling, but not exclusively.
It sounds like a refresher briefing at the start of the ride might be a good idea, especially from a founder like yourself? As annoying as that is to do, it's probably less annoying than having someone shout "car up" repeatedly on busier roads (the delegated back-marker / tail-ender should decide what merits a call) or point out every gutter drain cover you pass in a town.
The easy-rider/freewheeling group I ride with does use car up/down and hole calls sometimes, but the car ones more when on small quiet roads and the pootleton drifts around chatting, so the back-marker hears them quite a bit sooner than others. I think that counts as warnings of the unexpected, because we often ride for miles around Norfolk without seeing a motor vehicle. If it's a busy road, of course there are cars and I feel they make quite enough noise without us adding to them!
The only call I dislike is people calling "clear" at junctions, especially when it's only clear for them. I think we should let everyone make their own decision unless the junction visibility is really awful. I fear calling "clear" may risk the next rider slowing correctly for the junction and a started-with-racers rider behind thinking they'll proceed because it's "clear" and crashing into them. Not that I've seen that happen yet, happily.