It was only not long after that when Mozilla's fresh direction decided to start pushing the WebExtensions bandwagon only while dropping everything else, in spite of the thousands of man-hours invested by the addon developers (many of which, you can understand, were not happy; see http://fasezero.com/lastnotice.html )
>they had to ditch the old extension model
To me, that's more like a political decision they made at an arbitrary point in time.