The purpose of a coinjoin is to protect your on chain privacy, it's not difficult, the client does all the construction and signing of the transaction for you.

Normies who aren't interested in privacy would be able to benefit by using the coinjoin transaction as a non custodial scaling layer. The inputs registered to a coinjoin round are converted to an ephemeral ecash token that you can respend before the round ends and the coins are settled on chain. You can read more about this technique from this thread: https://x.com/MrKukks/status/1619294492854747138