I'm pretty sure the primary driver of that was Google turning Chrome into shovelware bundled with Adobe Flash and marketing it aggressively.
Mozilla has never been a competitive company. They've always leaned heavily on the illusion of being a non-profit. They've always sold the "eat your vegetables" version of web browsing, without actually offering anything compelling over the competition. We're just expected to use Firefox because "it's made by not-Google".
You were clearly the issue in the other thread.