To be fair on Mr Frog
A) you do post a lot of opinionated crap that a lot of people disagree with, usually followed up by insulting anyone who counters your opinion. Characterising someone as a naive middle aged man is hardly likely to endear you to people is it? Some might even say it’s a bit naive for a middle aged man.
B) the original point that plenty of people bought 4″+ bikes and discovered that width actually had far less effect on rolling resistance than they thought (Jumbo Jims actually have the same rolling resistance as 2.1″ 120tpi Small bLock 8’s) is correct. I’m not sure how much manufacturers learnt from it (kenda’s fat bike tyres were just as bad as their conventional ones), but consumers certainly did. I was trying to buy some 2.0-2.1″ tyres the other day, the choices is really quite limited, even XC race tyres that are made in 2.0 sizes don’t actually appear on shops shelves. Maxxis <2.2 and Schwalbe <2.25 are like hens teeth unless you buy the top of the range race tyres.
The myth of skinny tyres being essential for mud seems to have been debunked, I was out on Sunday on the Vagabond with 2.1″ SB8’s and had a far easier time riding through the mud than the pure CX bikes.