Because that's a lie and that's their only marketing, resting on their goodwill from when they actually cared and did meaningful things about that stuff.
Netscape may be. Mozilla is the child of some influential hacking community that spun off, back in the early 2000s that then found a lifeline in Google ad money. Since that phase passed, they've still siphoning off those laurels for the next two decades.
Please don't send Mozilla your money...everyone's donations before then went to exec millions of dollars per year salary.
Mozilla is sitting on $500M cash reserves + $500M / year from Google. Don't assign lack of money as the real reason of MDN falling: lack of product direction and leadership.
This is true. Execs at the non-profit foundation have been pocketing millions of dollars. And I cannot really point out what they do. I guess this is common in many non-profits, where people donate, and people at the top siphon it off. There's some corruption at play at the top.