I think the problem here is using solely color to distinguish connections. Ive definitely seen schematics where, if printed in B/W, are impossible to read.
> ...if electrical intent cannot be cleanly and unambiguously conveyed in black and white, it's garbage.
The problem isn't just constained to connections though: consider adjacent symbols, components symbol elements vs. nets, nets vs. busses, components in which physical color is a salient characteristic, etc.
