That is true.
At some point (2/2019) it became unsafe to call pinMode() in a constructor and shortly after (11/2019) also disallowed to call detachInterrupt() from within the ISR, hence it was required to move these calls into a explicitly callable function.
However, that call is also present in the library examples. So whenever moving on to a newer version of a library it's advisable to also check the provided samples against your legacy code.
About the post you linked, that was from before the addition of DHT.begin() and since the OP never responded to my suggestions it's hard to tell what the cause actually was.