ActiveX isn't a major concern, in current IE if you look in the security tab in the Internet context, it is pretty locked down and damn near depreciated.

Intranet is more liberal. But a lot of enterprises add their internal portals to the trusted list if they still depend on ActiveX (as a depressingly large number do).

Chrome and Firefox's extensions are better. Although Firefox's extension model is a little clunky due to how old it is (or at least it was last time I used it).