Definitely a good idea for Windows users, and possibly Macs as well (I don't know the prevalence of browser-infesting software there).
On Linux, though, it promptly flagged all of the addons I had installed through the distro packaging system as "third-party addons" and wanted to disable them by default.
so it worked properly on Linux.
there is no way to know whether an addon instaled 'for the whole' system was added by third party, or by package. only addons in Your home dir are considered as 'installed by you'
Except that Linux doesn't tend to suffer from the browser-infesting stealth installs common to other platforms; the case of packaged addons seems far more common and likely.
On Linux, though, it promptly flagged all of the addons I had installed through the distro packaging system as "third-party addons" and wanted to disable them by default.