If the extension cannot access the network to send data anywhere, what's the worse that could happen in that scenerio? Obviously some extensions have good reas

If the extension cannot access the network to send data anywhere, what's the worse that could happen in that scenerio? Obviously some extensions have good reason to use the network, and there's no easy solution there. Some extensions change a color them on a page and that's it, I wish those could be denied internet access.