I think if possible there should be three types of ranked matches/modes:
- human versus human only
- mixed mode (everybody - humans, bots, aliens, cats, ..., - could join) :-)
- bots only (also the pure machine contest could be interesting if separated from human competition; similar like in chess)
Bot vs bot could be interesting... Similar to watching Stockfish vs AlphaZero and their unique strategies. I imagine the game needs more complexity to reach anywhere near those levels though. Maybe after spells and more rulesets are introduced! Thanks for your comment.