Well, ActiveX was a proprietary technology developed by Microsoft that only run on Windows, and especially only run on IE. So sites using it were only working w

Well, ActiveX was a proprietary technology developed by Microsoft that only run on Windows, and especially only run on IE. So sites using it were only working with IE. Webkit and Mozilla being open source means that no single company can control the projects or add a proprietary single-platform exception to them. Now, a company could FORK Webkit/geecko and add something like ActiveX to it, but the fork wouldn't be part of webkit/geecko project anymore, and we'd still have webkit/geecko proper. For example, Google added NaCL which is something like ActiveX to Chrome, but not to Webkit itself.