I dont think it is deliberate. Or for security reasons. The new system has been applied across the Catholic Education of Paramatta, so all schools under that get it. Its more so they haven't designed it that well. And the IT isn't going to be able to help because they don't design or run the system, and they honestly seem to have no idea what they are doing with anything...
Things such as steam aren't blocked. Facebook etc are. If we were still using the old system where you just connect then do what ever you need it would work fine the connection would be available to any app on the computer. But because you must log in it ONLY logs into the program you are using. In this case, Chrome, not the entire computer.
Basicly what happens is; you turn the computer on and open chrome. Try to go to a page such as google and it redirects you to a login page. Then type your school username and password and press login, then redirects you back to whatever page you were trying to access. So therefore if I open steam, because steam has no visible browser, when the steam client tries to access its servers, the network redirects it to the login page, but i cant see it because its all happening in the background.
This is just a random pic off the internet, not related to me: 
This is the window that opens on ipads and iphones when you connect to a public wifi. the login window.
Is there somthing like this on mac? If there is, it will solve all the problems and all programs will work correctly.