MTB's are high peformance bits of kit too
No they're not. Not compared to an F1 car, or a spaceship, or an aircraft carrier or something. They're just bikes. Simple, relatively low-tech moderate performance machines. The rest is just marketing gumph.
Tyres? A set of mud tyres are better in winter sloppiness, but other than that, I'll just slap on whatever's cheap on sale somewhere. I ride 'em until the tread's worn right down, or they've got cuts and tears in them.
Yeah, if you're racing, then the lightest tyres might give you an advantage, sure, but for the vast majority of us, any old bit of rubber with some tread on will do for most riding. I spose heavy duty ones will be tougher on sharp rocks and that, but there's not a lot in it really.
The rest is all marketing gumph.
People dunalf make a load of fuss over tyres. Probbly cos they want to look clever. Best off just riding yer bike about really, than waste time changing tyres over for every single ride just cos the terrain's slightly different.