Google Disables Inline Installation For Chrome Extensions (venturebeat.com)
An anonymous reader writes: Google today announced that Chrome will no longer support inline installation of extensions. New extensions lose inline installation starting today, existing extensions will lose the ability in three months, and in early December the inline install API will be removed from the browser with the release of Chrome 71. Critics have pointed out such moves make the Chrome Web Store a walled garden, while Google insists pushing users to the store ultimately protects them.
If you've ever seen a regular Chrome user's computer, you know there's at least one rogue extension that they can't explain how it was installed. More likely, several - and one of them changing the new tab page or redirecting searches away from Google.
Inline installation just refers to installs from a website. What you are talking about can be done locally using the extensions tab in dev mode.
So that's why Firefox has been becoming more and more Chrome-like, so it can be an alternative to Chrome after this change!