"I am okay with pedoshit but I draw the line at diaper play" Weird purity standards.
Honestly I think some kinks are trends, socially contagious. Some of those people They never knew they were into this or that, until they met the type of deviant shit that scratch their itch, and/or starts associating it with arousal.
The Japanese that are into related stuff could get there too after a while, if the online spaces start colliding. It's not like America considers used diapers an acceptable form of adult attire. It's the transgression / desecration /humiliation aspect that turns them on.