Firefox already captured the developer audience, and it wasn't enough. So they pivoted to whatever they thought of to increase mainstream adoption. That is really alienating that developer audience though.
Firefox had mainstream adoption in the Firefox 2 era, before Chrome launched. What drew people to Chrome was that it was fast, efficient, and did I mention fast? Unfortunately all browsers today seem to have forgotten how important that is.
The whole purpose of Chrome is to have google search by default in people's browsers. Once they have a large market share nothing else really matters. If people truly cared about speed Google would have changed it already.