Chrome currently has the largest amount of extensions, which is an advantage for that browser.
Standardized WebExtensions dilute that, because they allow easy ports to the other browsers.
I think the point is more, in what way does google have any power to stop other browsers from implementing this API?
I just don't see how any of that is relevant to the original comment I replied to:
> But will Google allow this to happen, as it would strip them a huge selling point for Chrome?
In what way would standardizing WebExtensions, which are already supported by all modern browsers (sans Safari), strip Chrome of selling points?
Why should Google have to "allow" this?