> But aren't we all here because we like inference and brevity?

Inference: On condition it is _controlled_.  I.e. seeing operator
<foo> used on a complex type, I need to know I have seen its
definition and satisfied myself that it has the expected semantic
properties.  That's just what functors formalize.

Brevity: There's the pesky tradeoff with some type annotations being
required when you introduce overloading.