I dunno. Something like spec, dialyzer, or "assertive" typing (in the case of Elixir) on the boundary works just fine for me.

Microservices just push the problem out of sight — now you need interoperable types between them, there are race conditions, IDEs don’t see inside the black box of other services so refactoring is harder, etc.

They can be the correct solution sometimes, but blindly applying them everywhere is just dumb.