Good for you, but you're not the only person working on the codebase, surely.

>My function bodies are generally only a few lines, but my reasoning here is based on the choice of identifier name.

Your short functions still call other functions which call other functions which call other functions. The type will not always be obvious from looking at the current function body; often all a function does with an argument is forward it along untouched to another function. You often still need to jump through many layers of the call graph to figure out how something actually gets used.

An identifier name can't be as expressive as a type without sacrificing concision, and can't be checked mechanically. Why not be precise, why not offload some mental work onto the computer?

>Yes, it takes discipline, but it's the same kind of discipline as adding type annotations.

No, see, this is an absolutely crucial point of disagreement:

Adding type annotations is not "discipline"!

Or at least, not the same kind of discipline as remembering the types myself and running the type checker in my head. The type checker is good because it relieves me of the necessity of discipline, at least wrt to types.

Discipline consumes scarce mental effort. It doesn't scale as project complexity grows, as organizations grow, and as time passes. I would rather spend my limited mental effort on higher level things; making sure types match is rote clerical work, entirely suitable to a machine.

The language of "discipline" paints any mistake as a personal/moral failure of an individual. It's the language of a blame-culture.