I think it's weird that one Mystery allows you to infinitely play any number of those cards. I feel sacrificing a Mystery to play one of the cards exiled with intrigue would make getting further Mysteries meaningful without further built-around (than already being an A/B mechanic).

I am unfamiliar with the phrase A/B mechanic and do not know what you mean (my guess is something like Corrupted, that can only exist off of something else?).

I had not considered sacrificing the Mystery to play the exiled card, because I was already in a mindset of worry over parasitism. That pushed me to try and use Mystery tokens as a resource so that more cards could make use of them and they weren't only there to exist to enable plays from Intrigue.