IVs were first derived by either Sewall Wright or his dad (there is some disagreement on this point). I don't think they formally understood interventions in general back in 1928, but they understood causality very well in the linear model special case.

IVs can be used in more general models than linear, and the reason they work in such settings needed formal causal math to work out, yes. IVs recover interventionist causal effects.