Your claim is really a massive oversimplifaction in a very complex area.
Thanks for detailed answer. Definitely I oversimplified based on personal experience more than anything. Although, I do have some power data to compare efforts vs tyre set up as well, although, too lazy to switch tyres and stuff on the same day to compare in identical conditions. Plus, where I live, identical conditions don't necessarily last long.
I was certainly old-school, putting as much pressure into tyres as they could bare for a long while. Used to use 22mm tyres on a tandem many years ago, pumped to their limit. Didn't have power meters and bike computers in those days, but we thought they were cool and fast. After many years without riding, but renting Brommie, after the marathons lost a little pressure, felt like riding through treacle, so used track pump at work to get back to 100psi. Pretty much used that with most tyres I'd tried on my own brommies, for years, even with the sluggish rough road, energy sapping, descents.
But after switching to tubeless on road bike during lockdown, started to enjoy lower pressures for speed, grip and comfort, and realised, brommie conties run pretty well at those pressures too. And when you think about it, surely with smaller wheel, you'd want slightly lower pressure than you'd want with equivalent 700c with clinchers (when the hell did that word become a thing?) to take the bumps in the road better?
Aero hardly comes into it on brommie unless you get aero rims, and still, come on... it's the scary TT bars that I'm not even going to try with my brommie, unless I can get a couple laps at Maindy, to get any slight chance of me being aero (will make excuse that they don't quite fit anyway... I didn't try... just guessing.. don't want to try... scare me occasionally on road bike ... even with free watts ... see what happened to Chris Froome and Egan Bernal?).
Wider tyres are not necessarily less aero, depending on the width of the rim they're attached to, and the aero-ness of the rim. Aero rims are getting wider. Let's face, it's the rider not the tyres/rims that make biggest aero impact, and having fast rolling, wider, more comfortable, controllable tyres/rims seems to be becoming more the norm. At some point, world tour will be running the same size tyres us brommie riders have been running all along, and trying to do skinny tyres for a brommie without there being a track series was just a mistake.
I guess, making a tyre that can take a large amount of pressure is important, but running it at that pressure isn't the point. Certainly, I want the margin of error. Hookless rims suggest much lower maximums that we used to try and stuff into the tyres of borrow bikes at HHV in late eighties. But those Geoffrey Butler track bikes must've had 30mm at least tyres on them, not slick at all (HHV surface wasn't brilliant then), but damn, they felt so fast.
My over-simplification is, those contis don't half roll well for brommie at variety of pressures and I'm not going to jinx myself anymore than that!
Also, in simple tests, with power meter, didn't get much different with tubolitos vs butyl, but tubolitos are more of a pain to get pump off (also don't really colour match the bike), but WAY smaller/lighter as a spare. Didn't help me in last year's UHC, but that was down to lack of appropriate training.