I'm not sure that's true. There are alternative possibilities: That one learns to predict (some kinds of) people. That one's obsessed with a series of topics that gets oneself bored when not being able to discuss, etc. There's many, many small reasons an introvert's energy is depleted, that is not just "being with people".

As an anecdotal data point, I was very introvert and I did learn to "be extrovert" and many people wouldn't notice at all, but at the end of the day I need to be alone, sometimes for days to recover and be productive again.

Even though it's anecdotal I think we can't generalize and say "introversion doesn't exist". There's a lot of factors involved. Stuff may be even more complex when dealing with an ASD.