kigmatzomat
Legend
I mean yes, it's true that elves live that long by default, but their whole sociology and ecology are centered around that. Elves seldom have kids and even more rarely set off to conquer the world. Plus, 'Clone' is likely seen as redundant to an elf since elves reincarnate after spending time in Arvandor. I kind of imagine Elves would find it gauche to cling to a single life by preserving it with Clone.
Arvandor is a Faerun specific thing. I don't see any mention of it in 5e core books. Its definitely not in Eberron or Krynn and pretty sure it's not Greyhawk.
So that particular view of elven society is setting specific, even within WotC lore. Their lifespan, trance, and physical maturity at 20 but reaching "adulthood" at 100 is universal. After that? Check the setting book or the DM, because it's probably going to change.