Early immobilizers were just resistors, yes. (e.g. GM VATS) However, later "chipped keys" do use strong crypto over short-range wireless.

The "fobs" in modern push-to-start cars actually have two separate radios in them. The one that this article is about is the long-range keyless entry radio, which primarily opens the doors. These all have separate short-range wireless radios that work inside of the car to authenticate the key before you can press the push-to-start button. That is unaffected by this hack.

Thanks for that info. OK, then i'll double down on my criticism of the G_G_G_P, a "real key" for the ignition is not safer by any reasonable criteria, since the crypto part doesn't occur through the metal of the key (resistor style), but wirelessly. The key is just annoying.