When travelling on roads without a shoulder it's safer for everyone if the group makes itself as short as possible which requires taking the lane or at the very least riding two abreast.

Absolutely true. When I'm not on a bike, I'm driving the same roads and the local clubs love the roads near my house. With limited passing opportunities given hills and turns, it's much easier to pass of they ride two and three abreast taking the entire lane. If they were single file, you'd never find a space to pass.

Just remember cyclists may occasionally piss off motorists but we seldom endanger their lives. On the other hand, motorists frequently hurt or kill cyclists. I think your anger is misplaced.

OTOH, that sounds like little more than a weak rationalization for poor behavior. Which I see repeated ad nauseum in these threads. I can only shake my head in amazement that anyone that as a serious excuse.