Well, there is a browser setting to disable that feature. But in any case, the extension can block "behind-the-scene" requests if a user choose to:

https://github.com/gorhill/httpswitchboard/wiki/Behind-the-s...

By default all behind the scene requests are allowed (or else that would break auto-update and other extensions), but you can make it block everything (except of course for those net requests which are not routed through the chrome.webRequest API).

It is quite useful to also see (and control) net requests made by other extensions.