Docker docs:
Docker routes container traffic in the nat table, which means that packets are diverted before it reaches the INPUT and OUTPUT chains that ufw uses. Packets are routed before the firewall rules can be applied, effectively ignoring your firewall configuration.
Sure but thats an angular app, and you already know how to manage its environment.
People self host all sorts of things, with dozens of services in their home server.
They dont need to know how to manage the environment for these services because docker "makes everything so easy".