While technically true, the P4 did support PAE, in reality you couldn’t really make use of it on consumer hardware for most of its lifetime. No ordinary socket 478 mainboard with DDR1 memory supported more than 4 GB of RAM. With socket 775 more RAM was possible, but that socket is “only” ~20 years old.
Besides that, there were other even newer systems that supported only 4 GB of RAM, like some Intel Atom mainboards with a single DDR2 socket. Same with Via C3 mainboards.
Then I don’t understand what your point is. A CPU on its own without a system isn’t of any use. Since there were no motherboards allowing you to use that much RAM, the point about the CPU supporting it is moot as far as I am concerned.