Is there a reason why typeintersect constrains the args using type assertions in the method body instead of using dispatch?

Internals & Design Internals
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This is the definition of typeintersect:

typeintersect(@nospecialize(a), @nospecialize(b)) = (@_total_meta; ccall(:jl_type_intersection, Any, (Any, Any), a::Type, b::Type))

It seems like the following would be an improvement, because an exception would be thrown sooner when any of the two arguments isn’t a Type:

typeintersect(@nospecialize(a::Type), @nospecialize(b::Type)) = (@_total_meta; ccall(:jl_type_intersection, Any, (Any, Any), a, b))

Is this just because of backwards compatibility and the distinction between TypeError and MethodError? Or maybe it’s some kind of bootstrapping-related limitation?