The performance of pretty much every PHEV I've seen is abysmal. The people buying a Model 3 or Model S to replace their BMW or Mercedes aren't interested in something with the performance of a geo metro. So, while on paper a PHEV solution might look better, in the real world it would result in those people just going back to regular ICE. If you outlaw ICE/make those cars unavailable, you'll find plenty of political headwinds and set the entire movement back a decade IMO.