I don't think necessarily everyone who likes loli or shota are also MAPs, but there's obviously a very large overlap between the two.

IMO most people who do this are either just trying to save face or are in denial about their attraction. You'll often hear from gay people how they thought they were straight and were in denial about their sexuality for a long time before accepting themselves, so I think a big chunk of the people who say they're lolicons/shotacons but not MAPs are having the same experience because society is extremely antagonistic towards MAPs.