But currently all phones have an exposed screen ??? You have to go back to clamshell phones or blackberry designs to have protected screens. If you don't buy a shell or screen protector, your screen gets rattled by coins, keys, and various objects.
Current non-foldable phones have gorilla glass on top of their display.
bendable screens are made from plastic rather than glass, so it's worse than your typical phone.
And more to your point it is soft plastic and not hard plastic.
If you have a case on eg. an iPhone then it extends slightly beyond the screen at the sides, which probably makes quite a big difference in protecting particularly the sides of the screen.
The edge will likely take more abuse than the surface of the phone. Plus it will be impossible not to have fingerprints on it.