Latency on calls over cellular networks is already very high (my subjective experience). But we humans are good at working around it when it's just two people

Latency on calls over cellular networks is already very high (my subjective experience). But we humans are good at working around it when it's just two people - wait for the other person to finish speaking before you speak, and the other person might have a little longer delay before hearing your response. If there are multiple parties on the call, this breaks down, because if two people want to speak, they both start talking and don't realize it for a little while. On video calls this also breaks down, because either video and audio get out of sync (like with zoom) or you get odd artifacts in either the video or audio as they are kept in sync.