> Printer cartridges were even signed against the printer themselves.

Printer cartridges used to be dumb and replacable by mechanically identical 3rd party products.

> And walled gardens aren't weird. It has always been the default. I can only install console games approved by Sony, Nintendo etc for example.

Those are gaming devices, not general purpose edge computing devices under which smart-"phones" fall for all intents and purposes. Personal computers are a much better reference point.