More correctly, users cannot download anything from another source and try to install it on the Chorme browser. By going through the Chrome Web Store , Google thinks that this will prevent malware from issuing extensions to Chrome users.
Malware can make your browser appear unwanted pages, browser crashes, slow browsing speed and many other problems, but Google says the move of When we do this, it will help you browse the web more safely and it will remove all unwanted things that appear on your site.
In addition, according to Google " All extension software will be automatically turned off, you will not be able to install or re-install it until we finish reorganizing Chrome Web Store ".