I asked a similar question about a year ago on Reddit (which I don't use anymore after I learned how crass management was conducted in the company). I didn't take the time to read your article in depth, but my understanding is that there seems to be an "Firefox Doomsday" article written every year. If I remember correctly, I was pointed to a graph showing the number of users of Firefox over the years, and roughly, the numbers are always increasing. Albeit slowly, but still increasing. I'm not sure what the aim of these articles would be.
I can only speak for myself in saying that Firefox is clearly faster than Chrome. Especially with the fact that I use more than 4 monitors on my system. Every Chromium based application manages multiple monitors horribly and is slow. And there's also the fact that Google seems to want to change Chromium to make it so the viewing of Ads is mandatory (preventing any Ad-Blocker from working on their platform). Plus all the Cookies, Trackers and Surveillance that happens online, Firefox is the clear winner in this race.