I think Facebook did a study that making options opt-in means only a tiny tiny percentage of users will ever activate them. People never look around in settings.

I suppose if - after you click away the popup that says "Thank you for loving Firefox"(1) - a popup shows that says "Hey, hey, look at me, look we have this new feature, it'll blow you away. Do you want to enable it?" would be obnoxious but satisfies the idea of "opt-in".

(1) https://bugzilla.mozilla.org/show_bug.cgi?id=1791524 - I still remember how icked I was seeing this popup.

Don't need to run studies to understand that.

If it's off be default it will stay off unless the user is somehow made to try it. Default opt-in is one option to do that, the simplest one, but it's not the only one. The rest require explaining clearly what the user will get out of enabling it ... and that often is difficult to do succinctly, or convincingly. So shovelling it down everyone's throat it is.

> making options opt-in means only a tiny tiny percentage of users will ever activate them

Why exactly should I, a user, care about this? I don't want useless crap shoved in my face, period. I don't care that people might not turn on someone's pet feature if they don't enable it by default.

Yes, that’s the intent of the argument. If it’s so valuable , people will find it, talk about it, amd it’ll spread on its merits.