Not entirely true: for WPA2 it is the case that all APs and clients use the same key, but even in that case, 11r adds mobility domain and FT-PSK and results in

Not entirely true: for WPA2 it is the case that all APs and clients use the same key, but even in that case, 11r adds mobility domain and FT-PSK and results in more devices having better roaming. For WPA3-SAE and WPA3-OWE it is required as each client has a different (session) key.