You’re talking about Thunderbird, a project they basically abandoned to the community. Thunderbird survives in spite of Mozilla, not because of it. Meanwhile their main product Firefox is still bleeding users down into the single digit percentages while receiving half a billion a year from Google. It takes a lot of skill to run such a company so deep into the ground.
The entire goal is to use money to change your behavior. They’re inherently manipulative by definition. It’s literally weaponized mass manipulation. There’s no way to spin that as a positive effect.
If you think about it in terms of it’s effects, advertising is the closest thing we have to mind control: companies are paying money to change the behavior of millions of people. Even without any concrete examples, you can easily see how dystopic it really is when you just think about the intention alone