It is entirely unlike and yet similar to...

Is the distinction between supply and demand tokens unnecessary?

Keeping the distinction has two results, both minor. 1) It is easy to ensure that there are 3 supplies for every demand while also having a somewhat random setup. 2) It allows a blocking tactic in which multiple demands are grouped around a small number of supplies without satisfaction, thus driving delivery traffic in that direction. While I really like the tactic, I’m fairly sure it is not enough to justify an entire mechanism and related complexity.