One of the biggest issues players have creating maps is not being able to test it unless they have 1 or even multiple people to test it with. I think a good solution for this issue would be the ability to add AI that just stand still (or potentially other behaviours like attacking, randomly running)
Dummy players would definitely save us lots of time trying to find players ourselves to test different mechanics and it doesn't seem like it'd be incredibly hard to do for the value it would bring (imo)