[dblohm7]

This being HN, I'm operating under the assumption that most readers are developers.

I'd suggest that you read my colleague's comment at https://news.ycombinator.com/item?id=15696184 to understand just how much friction the legacy addon ecosystem was creating. It just wasn't sustainable.

[SllX]

You won't find me arguing against Mozilla's decision to drop XUL extensions, I'm just stating a fact, that it was one of the primary differentiating factors between Firefox and its competition, for better because of the varied high quality extensions that you simply would not find anywhere else and obviously for worse.