Nothing in that comment discussed plugin hybrids though.

A non plug-in hybrid will be more efficient than a full gas vehicle because of the efficiency you can gain through minimizing the engine and tuning it for a more limited rpm range.

This ideally carries over to a plug-in hybrid in the same way even if it’s never plugged in, if all the gas engine does is charge the battery it can be more efficient than a gas only car due to reduced engine size requirements.