Facebook is a panopticon with a massive dataset on each user, and has a pretty substantial moat by way of users 'punishing' each other for leaving, among other competitive advantages.
Snapchat is a trendy app that could easily become uncool, and when it does, I don't see how users feel much of a penalty for leaving in the same way FB users do.
I think it's because you might lose contact with people if you don't have a FB profile.
If you're not on FB and don't interact with your 'friends' frequently, people kinda forget you exist and stop talking to you, and friendships wither. Even geographically close friendships.
For the record, I have never used FB. I hated it from go.
I also can't point to any real studies; all I've got is anecdata, much like your personal experience.
That said, I have heard from multiple people variations on trying to quit or use it less, and getting grief from family and friends for not taking part. And I personally get passive-agressive commentary from my family for refusing to take part - "What did you think of - oh, that's right, you never saw [cousin]'s baby pictures because of your Facebook thing."
That is excellent for you. But you are not the world. I interact with people I'd label as "friends" where Facebook (or Facebook Messenger for some) is the only avenue I have for that interaction.
And for some, it's the only avenue I'd want to use.
I never said I was the world, but please take my statements in the context of close personal relationships.
If ones requirement is to maintain acquaintances, then fine. However, I was disputing the parent comment's assertion that leaving FB is akin to a punishment.
Snapchat is a trendy app that could easily become uncool, and when it does, I don't see how users feel much of a penalty for leaving in the same way FB users do.