I have maintained some mini projects which try to have strong API stability. And even through keeping API stability is much easier then ABI stability I already

I have maintained some mini projects which try to have strong API stability. And even through keeping API stability is much easier then ABI stability I already ran into gotchas. And that was simple stuff compared to what some of the more complex libraries do. So I don't think ABI FFI stability ever had a good chance (outside of some very well maintained big system libraries where a lot of work is put into making it work). I think the failure was to not realize it earlier and instead move to a more "message passing" + "error kernel" based approach for libraries where this is possible (which are surprisingly many) and use API stability only for the rest (except system libraries). EDIT: Like use pipes to interconnect libraries and use well defined (but potential binary) message passing between them. Being able to reload libraries resetting all global state, or run multiple versions of them at the same time etc. But without question this isn't nice for small utility libraries or language frameworks and similar.