I agree it would not need supplements. But if someone doesn't like eggs and meat, no problem adding some protein powder to their food. Not needed but makes it easier....
I eat relative low carb (not keto) and like eggs and meat so automatically I have enough....But there are some odd days, when I trained hard and someone sent me fresh fruits, than I drink an protein shake....Wouldn't be a problem to have a day with too less protein but having enough may help with recovery.
When ridding a lot bicycle (around 100km/day) in the heat in Thailand it might be needed to add minerals. But not many people do that