I guess my surprise comes from the fact that I come from a lifetime of programming in weakly typed languages. These are all about the number of arguments - so methods with 2, 3, 4, etc optional arguments will not “leak” 0 arguments methods that overwrite each other. Arity is a core concept there.
In the same line of thought, this is a fairly low level implementation detail, as I have no idea how ruby, or PHP or JavaScript handle methods with optional arguments. I doubt many devs do, as with more mature / older languages people work with higher level frameworks and DSLs which require a massive time investment and level of mastery of their own.
As Julia will go mainstream it will be more and more about higher level frameworks and DSLs and books about these, and less about Julia itself. Ask yourself how many Rails users (not contributors) have read the ruby manual?
It’s in this context where possible traps need to be avoided - and this is probably an ingredient for large scale adoption.