> A backwards compatibility switch to override the change would have been the least. They changed so much in the code base which broke compatibility with the o

> A backwards compatibility switch to override the change would have been the least. They changed so much in the code base which broke compatibility with the old system that they would have pretty much had to do a hard fork and include both Firefox versions into the download in order to provide this; pretty much doubling maintenance cost as well. On the flip side, they do now actually have an actual extension API, abstracting away from that code base, making it much more unlikely that such a breakage will be necessary in the future, and it especially also prevents those frequent smaller breakages that were commonplace with every new Firefox release up until 57.