Facebook makes it easier, but it is not like friends did not keep in touch before Facebook. I regularly send SMS/ email friends I make it point to spend writing and replying to mails regularly.
Sure, occasionally people get frustrated that you are not on these platforms, however I ended up being lot more responsive and attentive to non social media forms of communication. Social media is usually low effort, I rather have one person wishing me with personal email on my birthday, rather than hundreds of meaningless FB posts.
It was actually harder for business contacts than personal, customers want to chat in whatever works for them, harder to say no to someone paying you. However Teams/Slack has helped a lot and dose of compliance reasons which customers find easier to go along with.
It’s hard though, because what alternative do people have?
I didn’t log in to my Facebook account for 7 years, and I got way out of touch with most of my old friends in different cities.