I can see the argument against acknowledging other cyclists in a busy setting. But it's the ones I come across in the middle of nowhere, at the top of a long climb up a single track road for instance, with no other humans for miles around. Then a cyclist appears, makes eye contact so you wave/nod or whatever - and the ignorant so and so breaks the eye contact and completely blanks you!
I mean, dog walkers, hikers, even car drivers will give you the time of day in such circumstances - but not a fellow cyclist? Sorry but I just find that weird behaviour. Weird, but not annoying. It is what it is, as they say. But if you're stuck at the side of the road with a puncture next time I see you, don't look to me for help. 🤣. And mean looking, too cool for school roadies, you lot are the worst offenders.