The right set of coding conventions can improve readability and write ability. Like when he is talking about the conversion functions in the article, the cognitive load of XfromY is quite low. You don't have to consult the documentation to find out what it is called, or how it works, etc. You don't have to think about the name when writing it or how it should work. In a setting without conventions that function could have a dozen names, another dozen ways to arrange the args, and do error handling. There would be no way you would call it with out consulting the docs.

As far as encoding semantics in to the type system, it would be great and help eliminate bugs, it wouldn't do a single thing to reduce the mental overhead out lined above. Basically they solve the same problem by two different paths, one makes doing the right thing easy, the other makes doing the wrong thing hard. Full semantic analysis probably isn't possible in a reasonable way, but catching the low hanging fruit should be possible.