Suppose I'm on an approach in which the IAP leads me to the inbound
course at the correct altitude (no radar), am I supposed to execute a
PT? That doesn't make sense to me. ATC would not have authorized
anyone else to be in that airspace so aircraft separation isn't a
problem and there is no need to lose altitude or change course so
obstacle clearance shouldn't be an issue.

Maybe there are no such approaches, or perhaps all such courses are
marked NoPT.