This mode needs such strong teamwork, but no talking...
Also, since there's no regional match making, language barriers
If only people who want voice chat don't always talk about how they will give other people orders. That's the main reason voice chat with randoms don't usually work.
This is why voice chat for team matches come August absolutely need to be a thing. I can understand no chat with randoms (in a Nintendo game), but if they don't bring it with custom team matches that is a big miss.