Yes, there are no rides at WDW that are off-limits to adults only. Some other amusement parks, yes, not WDW.
I should add, US's IOA has ONE attraction that is only open for kids of a certain height range (plus an adult with such a child). I've never figured out why, but I think because it is tame and slow loading.
While I don't dislike PP, I kind of think it a bit over-rated sometimes. I think part of why it also gets long lines is the limits of ride capacity. Which increases demand and bragging rights. There aren't any big special effects on the ride. It is very much an old-style classic.