Proof that humans can get used to pretty much anything

My 100% BS conjectures are:

• to save energy versus committing the dream to long term memory
• to facilitate childhood/adolescent development, as object permanence is learned you need the external world to be the consistent one. You can't waste energy learning to adapt to the worlds in your dreams in later childhood.
• as adults dream amnesia can help avoid relived or newly generated trauma incurred as the begin processes your external experience.

Idk, there's lots of possible benefits. In not about to do the research paper deep dive. But the wild part is that dreaming developed and the mechanism for not remembering the dreams also developed and there was a selective pressure for that to be the case.