Most people who has Firefox installed is either installing because that's what they have always used or is using because someone recommended it. They have to be explicitly installed. Keep that in mind. Don't you remember firefox installation fest and stuff? That 1% pushes Firefox to non-users at home, in their companies and where not. That 1% is responsible for a lot of the rest of the 99%.
The folks Mozilla is trying to attract don't care for all of these. Their biggest selling point is privacy and being community friendly. If it's getting deteriorated, why should the general folks who don't know what Manifest V3 is install it?
Especially when tech enthusiasts are talking bad about it. What impression does it make to a non-tech guy who woke up one day drinking filter coffee and thought... Huh! From today onwards, I want privacy!!??
I agree most either have used it for a long time or because someone recommended it. It's nearly tautological. I disagree the recommendations for the average user only/primarily come from <1% of the user base or that's what makes the installs stick when they do. Power users desperately want to feel key to the success, but the reality is people stick with a browser based on what it does for them not how much it does for their power user friend who recommended it 20 years ago. The same is true in reverse: power users can comment here all they want about privacy nits or what Mozilla should do blah blah but it doesn't matter to the average user because they aren't reading tech forums for opinions on browsers. Most Firefox users probably couldn't tell you what Mozilla even is in relation to Firefox.
The 200 million normal users can also recommend trying to use Firefox all the time to their friends again, they just don't have a reason to do so because often, for their cares, Chrome and others are the ones with better target to them. Pre-installs is definitely a problem, as it always has been, but it never stopped Firefox before.
If the non-tech person wakes up one day and decides privacy is a key concern for the browser then they join the few that learn about each in this detail and pick from there and the niche has a new member. When things like 1,000,000,000 people wake up and decided mobile performance and battery life were important for years it resulted in Firefox having next to no presence on mobile more than any other reason.