And the soy plastic alternatives have caused huge problems in practice. Squirrels and mice totaling entire brand new cars by eating the insulation. Not to mention terrible longevity.
Yeah in a lot of ways the things that make plastics bad for the environment makes them good for electrical insulation. Primarily how they don't break down very easily, aren't particularly chemically reactive, don't rot, etc.
The knob and tube wiring in my 1930's house was still working fine. That tech would need to be updated for modern safety requirements (ground wire, etc) but worked without plastics for about 50 years. Much high cost though, I would guess.
Old wire is usually fine if it just sits there, but it may no longer be water proof or turn hard and brittle. That's why the failure mode is so unfortunate, it loses the properties you'd want in an insulator while still appearing safe.
