You cannot have "true" overloading in a dynamically typed language - the IDE cannot possibly show matching auto-completion because it has no clue what types variables or values are, and having a script do different things based on incoming argument is only fun up until you do so on accident.
#args schema is influenced by JavaScript's default parameters, as that's the safest way of doing this by a margin; both GMS and GMEdit support same syntax in function doc lines.