I think Nums is talking about the current coding complexity problem. For a simple operation like TF'ing a bot needs to have a number stored in .tieval, -1 in .tieloc and the number of the tie stored in .tienum. All of which is extremly hard for evolution to accomplish independently.
I was thinking of something similar to how the new tielens/tieangs might be useful. I was thinking that possibly storing a percent value (representing the resource type) to be transfered might be used instead of the negative numbers. The amounts transfered could be limited by bot strength, similar to what we do with shots; or increased with something similar to how shootval currently works.