The utility is not of existential importance. Yes, you can uninstall Facebook, Instagram and WhatsApp, and the sky will not fall, life will just go on.
Facebook is useful for bigger communities like moms groups. We found babysitters that way.
One of my social clubs tried to skip out of social media and was originally meeting in person, calling each other etc, but information just fell through the cracks as the club got larger.
Big tech literally has fingers in every single pie imaginable and it's real money for a lot of people, unfortunately.
Honestly speaking I would not be in a leadership position for my Toastmasters groups if I needed to call each individual member every week as my other Toastmaster club does. That probably says something about me, but I'm sure many other folks would have a similar outlook.
>> Similarly to how you can just eat less and lose weight.
I'd argue it isn't similar in an important way, people cannot opt out of eating entirely. Overeaters must eat. People who can't control themselves with social media do not need to use them at all.