Oh I've definitely been doing it for years, but only for things I don't care very much about. For example, I used to have a password protected livestream of a camera that was literally an ffmpeg command running in a tmux session that would pipe MJPEG data to an nginx instance, and tmux was by far the easiest way to get it going. But the moment I want reliability, automatic restarts, or something easily reproducible, I switch to systemd or a Docker container.

Main disadvantages: restart services if they crash (so run them in a loop); security and isolation of services from each other and the OS; restart services on reboot. I've solved these problems: https://tobykurien.com/simpler-linux-selfhosting/