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Google announced today that it made the decision to expand its non-Store extension installation policy to all Windows versions of the Chrome browser.
Back then, users on the stable or beta channel received notifications that unsupported extensions were disabled which meant that the browser had disabled all extensions not installed from the Chrome Web Store on launch.
While Google noticed a 75% drop in customer support help requests regarding uninstalling unwanted extensions afterwards from users of those channels, it did notice that malicious software forced "users into the developer channel in order to install unwanted off-store extensions".
Yeah, I'm sure that's the only reason.
Chromium here we come, I guess.