Repeatable content becomes a Chore when you have to do it daily or weekly.
In TBC Netherwing was a grind of repeatable content. You did the same daily quests for months until you hit exalted and could buy a faster flying mount. This was not a chore as you could ignore it (as I did until a few years ago when I went back and finished it off).
We’ve had plenty of other similar optional grinds. Cloud Serpent, Tillers, Kala’uk, Argent Tournament et al.
These did not gate player power, main story, flying etc. They were just something to do at max level.
Most of the grinds now are almost mandatory for either player power or simply access to the main story and even worse many need to be repeated on Alts. (9.1.5 is reducing some of the repeated content but not all).