Funnily enough I thought of like... Might and Magic, or Icewind Dale. Y'know, where you create the entire party yourself and they have no personalities of their own - interchangeable not-special adventurers that still go on to do big things.
This being a special trait, that's what gonna make them stand out and what people are gonna focus on. MC can, theoretically, eventually start using it to their advantage, too, not just someone else's. Their entire path can be (I mean that as a guess, as I'm not the author) at least partly about stopping being a tool and claiming agency for themself. Right now, they are lost, but they can grow.
I missed it, then.
It might be difficult to handle inner narration for largely customizable/blank-slate MCs, which is why it might not be used as much as with the more set MCs. One more reason I prefer partially-set personalities.