>Is it not possible for people to just delete the apps and stop using them?
Some people have friends, and some people also have friends that are very distant (geographically, life style, stage of life, etc).
Social media can allow you to keep in touch with these people in a very convenient way. For me, being able to see life updates of friends with 8h+ timezone differences is very nice perk, because planning a call or having energy to chat with someone that far away is tricky and many people understandably then drop it if that's the only way. (same applies if I want to talk to my digital nomad friend or, new-dad-overwhelmed friend). It's much easier to facilitate meeting up when I'm traveling too.
But even for people that want to use it for that purpose only, FB/Instagram will shove down infinite scroll and stories/reels/updates of people/entities you can care less about.
And yes for some it is hard to have "the willpower" as you want to frame it. (although we know it's not so much willpower, from addiction studies around nicotine and how loss of socialization around smoking usually is a detriment to quitting smoking for example)
And yes just removing / blocking those features help. There are also unofficial side-loadable app out there. So for me it works.
And for your life maybe there's no loss in socializing by just walking away. Good for you. But maybe the examples can shed some light in how social NETWORK (social media before algorithm and attention economy) is useful for many in different predicament than you, while the social media aspects, many would rather opt out.
And unfortunately only a select few of my friends (nerds/techies) are outside it (signal, discord, good old email) but almost everyone at least have an account. Many of the people I know move often enough that phone numbers aren't even a reliable way to keep in touch