That ensures your site will be up as much as possible. There are situations out of our control. Even many that have multiple backbones don't have automatic switching, so if the backbone your account is connected to goes down, your site is down. No TOS could possibly cover every eventuality. We don't try to list them as others do.
Most people act responsibly and know what's right and wrong.
If you have any doubts, ask first. Total responsibility for the content of your site. Hard drives fail, things happen, and keeping a copy is a smart precaution and aids in restoring a site. Protecting access to your account. This includes protecting your login and password, and any computers you use to access your account, especially if the password is saved on it or them.