with more colours it would not be more of a Problem to distinguish them? i don't mind, i just remember that this might be a reason in earlier discussions.
The real solution to the colour problem is to allow patterns rather than only solid colours. For a super-simple example, polka dots. But you could have just about any pattern imaginable. Even just simple stripes would be an improvement.
The colour problem was solved by flags and coats-of-arms in medieval times.