They're basically dynamic scoping and it's both a very useful and powerful and very dangerous feature ... scheme's dynamic-wind model makes it more obvious when the particular form of magic is in use but isn't otherwise a lot different.

I would like to think that somebody better at type systems than me could provide a way to encode it into one that doesn't require typing out the dynamic names and types on every single function but can instead infer them based on what other functions are being called therein, but even assuming you had that I'm not sure how much of the (very real) issues you describe it would ameliorate.

I think for golang the answer is probably "no, that sort of powerful but dangerous feature is not what we're going for here" ... and yet when used sufficiently sparingly in other languages, I've found it incredibly helpful.

Trade-offs all the way down as ever.