The fact of the matter is that you can do pretty much everything you want (within reason) using either 10', 11' or 12' rods. People are changing their 12's for 10's for no real advantage in most cases.
Personally I think one of the most overlooked aspects is for years practically everybody had a set of 12' rods and the tackle barons noticed this and decided to open up a whole huge market in trying to sell us something hardly any of us had and labelled them 'must haves'. The boom in rod sales must have been enormous, and of course we all 'need' an appropriate set of reels too.
Cynic, me? perhaps a little 😉