The checkbox does just that, it binds the application to the host network instead of using the docker network with a bridge to the host. In other words, binding an application to the host network allows it to “piggyback” on the host’s network configuration, using the same IP addresses and network settings as the host.
I cannot give an in depth answer as to why it is recommended to keep it disabled. Some apps do need to be bound to the host to work “properly”, like Tailscale for instance.
I am sure someone can give a much more in depth answer to your question.