Lifting weights and eating steaks
I think it has a lot to do with the fact that a lot of players can't actually afford to have a coach with them all the time. Which as you can imagine would be a huge disadvantage to the lower ranked players.How is anyone supposed to counter anything if you can't ask the coach for guidance? Every other sport does it. I'm a casual fan so I don't get the ruling. Explain it if you can.
To be honest, I hate the idea that a player can get advice and coaching during a match. Tennis is a mental game. They should be able to adapt to their opponent, if they cannot do this, they're not good enough on the day.
Who cares what other sports do. Tennis is a unique game with unique rules.