This is a good point. Look at 8.2 - Even the most hard-core grinders still dont have 8.0 mounts. 8.2 adds a crap ton of new collectibles, to a point where that mount you got in Darkshore is now pointless and bland (If you even got one...I dont, darkshore drop % vs Arathi is hilarious). To much to keep up with yes.
There are ofc grinds Ill never bother with like MOP world bosses, its fine to have insane stupid shit, but BFA add's to much junk grinds.