In my experience this really is not an issue. There’s an intentionality to using objects and you’re not a maddened fuzzer trying to plug random objects into arbitrary functions with no rhyme or reason.

It’s essentially a less likely version of using the wrong callback, something which has undoubtedly happened in the fullness of time but is of no real concern.

No in my opinion the issue is the opposite: implicit structural interfaces make it harder to discover what interfaces a type implements, and what you can do with it.

A secondary effect being that mismatches have worse reporting, whether you’re trying to implement an interface or the interface has changed from under you the compiler only reports use site so from there you have to did out what the type is and why it does not conform anymore, things get worse if side casts are involved. There’s actually a pattern for checking conformance:

    var _ Iface = (*Type)(nil)

Mmm yummy.

Oh yeah and if the interface removed a method and you didn’t realise you might be dragging that useless methods for a long while. Then again it’s not like your Java-style interface is any different.