Even if you ignore persistent sessions, there are some limitations with kitty's remote multiplexing functionality. For example some functionality relies on copying files, including executables, to the remote box, which may not be desirable or even possible. It also uses the ConrolMaster feature of ssh, which has some downsides, such as not being able to add additional port forwarding after the master session is created (at least on older versions of ssh, maybe that is fixed in a more recent version than what I use at work?).