Sure but you can also declare global arrays in Awk. The point is that Awk and bash are the same in several respects, so you don't really gain anything by switching to one or the other:

    - they don't have any garbage collection or ref counting
    - they don't have recursive data structures
    - you can't return any kind of array from a function

In bash you also can't pass an array to a function, but in Awk you can.