Sorry, I really cannot equate drafting with "riding like a dangerous nobber": the rider drafting has much greater risk and will take much more care in consequence. It is still sensible and reasonable to engage in conversation with your fellow riders without undue delay.
I'm not equating drafting with "riding like a dangerous nobber": I'm equating non-consensual drafting with it. I agree completely that the sensible approach if you want to draft is to agree it with the group ASAP.
I don't think you ride many sportives
@mjray (though you will be safer if you do as helmets are invariably required

)
I've ridden a few but they've gone to heck (due to many organisers taking too many entries, not providing enough support for the increased numbers, failing to take effective safety measures and failing to sanction dangerous nobbers) and since I gave up helmet use, they're mostly not an option, thanks to British Cycling's helmet compulsion.
and we've established on another thread that you don't think cycling clubs who want to ride along at a decent pace together (drafting!) have a place in your life so you have never had the chance to enjoy close cycling and the concommitant discipline and concentration required.
The bold bit is adding 2+2 and getting 5. While my health (edit: and to be honest, my attitude, which is now that going fast ain't worth concentrating on the bikes more than the views) means that I feel a racing club is no longer worthwhile for me, it's wrong to suggest I've never ridden in that style. I still do it occasionally among friends, but with consent (about once a year, by the looks of my ride tracking).
Using as a simile cars tailgating for cyclists drafting is a completely useless comparison: the former has no beneficial effect and lots of downside; the latter benefits at least one (maybe many if in a train) and with cooperation benefits all (all that is except people who wish to ride alone - all they have to do is to say politely while slowing down slightly perhaps 'do push on ahead').
Cars tailgating does have a beneficial effect: it give the following car a fuel economy advantage and slightly increases road capacity and that's why there's interest in "platooning" cars on motorways. Meanwhile, the drawback of cyclists drafting is a small probability of crashing in a nose-tail shunt: it's entirely fair for people to decide that a few mph more isn't worth enough to them to risk weeks off the bike while broken bones mend.