i worked as a computer technician in the 00s and encountered many varieties of fuckedup network hardware.

wifi isolation stops you from being able to run p2p in your own house, many devices have it on by default

there is less of them now but it used to be a lot more common that your router didn't have an internet address. worse with mobile devices. no address, no inbound.

many implementations of automatic port forwarding don't work with whatever it is you want to use it with

many firewalls require technical ability to open up the ability to listen to inbound connections just on your ethernet adapters.

i just finally found out how to disable wifi on my optical router in my house. it requires understanding enough to paste a javascript command into the debug console to achieve this. many times there isn't even a way to make the configuration allow p2p

idk what dream world you are living in but the one i see around me is not "easy p2p" most of the time. definitely not normie-level easy. in many cases, not even autist level easy.