I'm sure you've seen the figures that the average American drives ~40 miles a day. That's where the ~50 mile range PHEV battery comes from.
The question is what happens when you need to go further than that. On early EVs (like the GM EV-1), the answer was honestly to just find another car. That limited its appeal to just being a commuter/second car.
PHEVs answered that by including a gas drivetrain, although some now are just a gas generator. BEVs answered that by including a giant battery and enabling fast charging (as a concept, not necessarily as a product)