OOP is more involved than this. It’s not enough to inherit fields, but you need to verify contracts so types can be fully implemented and documented, and type piracy isn’t even possible. This is why Java is heavily used in enterprise, even though it’s an old language with few modern features.
I’ve published the following package Inherit.jl - Package Announcements - Julia Programming Language (julialang.org) which verifies type implementations, handles parametric types, while dealing with cross-module inheritance issues. But even there it’s far from complete.
It’s been a long way to speed up time-to-first-plot. I’m skeptical 1.12 can really make binary caching transparent. One purpose of breaking changes in 2.0 would be to prohibit invalidations. To keep up with other languages, Julia needs to gain general purpose developers who are good at building scaffolding around the language. Most Julia users who feel very satisfied currently probably haven’t seen it in an enterprise situation.