Why aren't "aliens" rarely used in more high fantasy settings?

Why aren't "aliens" rarely used in more high fantasy settings?

Because it's not sci-fi.

Obviously, but it's that far of a stretch. Plus you can work around all the typical sci-fi trappings to fit the setting more.

Do you consider Tieflings aliens? Or at least half-alien. I don't really see why other-planar creatures aren't technically aliens.

NEINNEINNEIN

Well, this actually.

D&D has plenty.

If isnt ever more a thing done was, then thing couldn't to be do that

This. D&D is full of alien shit. From outher space, dimentions, lovecraftian and even time traveler aliens from the future. Some like the Neogi have even fucking spaceships.

Do they count? They're more like inter-dimensional things

I guess it just feels wrong. Or at least, it does to me. I can deal if the setting is more gonzo/old-school (barrier peaks et al), but I feel mixing sci-fi and fantasy all willy-nilly fucks with thematic consistency.
The exception is for stuff like Endless Legend, where it's all coherent (the magic is just sufficiently advanced shit).

I'm going to be brutally honest when I say it makes me (politely) REEEE for some reason.
It's the same feeling I have for modern non-masquerade fantasy, and I cant explain that either