I’m also convinced that it is why GDC did not implement it, even if they probably thought of it. Otherwise, they’d need to allow tubes leaving the game field, and they don’t want that.
here is a good example of a protobot that does extremely well!
then this would just encourage more bucket hoarder bots 
Why do you think the GDC felt compelled to leave a tube removal strategy in the game? That’s a pretty strong assumption to make.
I just think that GDC wanted to eliminate an “easy way out” of tube removal. I’m sure they foresaw tubes being thrown under the ladder. With only about 20 of each alliance’s game objects on the field and descoring being feasible, it simply doesn’t make sense to have a starvation method that assures permanent starvation. Tubes under the ladder can still be accessed.
But you said if the ladder was a scoring area, the GDC would have to allow tubes over the walls. They could have the former but not the latter…