>The old extensions were not compatible with e10s. Addons based on older APIs could be made compatible with the newer multiprocess design (see https://develope

>The old extensions were not compatible with e10s. Addons based on older APIs could be made compatible with the newer multiprocess design (see https://developer.mozilla.org/en-US/Add-ons/Working_with_multiprocess_Firefox$revision/993443 https://developer.mozilla.org/en-US/Add-ons/Working_with_mul... ) and for a while Mozilla tried to persuade developers to update theirs (see https://blog.mozilla.org/addons/2016/08/02/multi-process-firefox-and-add-ons-a-call-to-action/ https://blog.mozilla.org/addons/2016/08/02/multi-process-fir... ) 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 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.