The over use of occupational licensing has some well documented negative effects, see https://www.econlib.org/library/Enc1/OccupationalLicensing.h... for some points about it.

However, physical therapists already have an occupational licensing exam. You could argue that it’s not hard enough, as it does have a high pass rate for those who have graduated from a PT university program, but then you start drifting into “no true Scotsman” territory.