While the corporate players involved may just happen to have interests that might align somewhat in this case, Mozilla has made its fair share of mistakes that have driven people away from Firefox. A browser with fewer users results in less influence for its creator and users, obviously.
Phoenix, Firebird and Firefox before version 4 were generally excellent releases. This was back when Mozilla innovated and put out offerings that benefited users. These versions truly made people better off, and much of Firefox's rapid adoption was due to direct word-of-mouth recommendation.
Then around Firefox 4, they decided to imitate Chrome, rather than leading the way. The release schedule changes caused broken add-ons for a very long time. This drove people away. They've also repeatedly made harmful UI changes, to the point where Firefox today is almost visually identical to Chrome. This has driven more people away. Meanwhile, there has only been minimal progress when it comes to improving the performance of Firefox, and reducing its memory usage. This, too, has driven more people away to browsers that manage to perform better, with fewer resources. (Spare us the are-we-fast-yet-style benchmarks that just don't seem to match the actual browsing experience.)
Nobody but Mozilla themselves made Mozilla act in such a manner. Nobody but Mozilla themselves are responsible for driving away so many Firefox users.
And so here we are today, with Firefox at perhaps 15% to 20% of the browser market, if even that. This is a far cry from their peak, when they were above 30%. They no longer offer an appealing product, which causes a decrease in the number of people using it, which directly results in the unfortunate lack of influence that we're seeing in this case.