I'm a bit of a hermit myself.

That seems like the problem and what's creating the perception making you agree with this.

I took a brief glance at the summary page on Wikipedia for the self-help book:

religious groups (Knights of Columbus, B'nai Brith, etc.), labor unions, parent–teacher associations, Federation of Women's Clubs, League of Women Voters, military veterans' organizations, volunteers with Boy Scouts and the Red Cross, and fraternal organizations (Lions Clubs, Benevolent and Protective Order of Elks, United States Junior Chamber, Freemasonry, Rotary, Kiwanis, etc.

Honestly wouldn't miss these if I knew what any of them are. They sound like weird cults.

Everett Carll Ladd claimed that Putnam completely ignored existing field studies, most notably the landmark sociological Middletown studies,[8] which during the 1920s raised the same concerns he does today, except the technology being attacked as promoting isolation was radio instead of television and video games

Sounds like he was reasoning backwards.

Other critics questioned Putnam's major finding—that civic participation has been declining. Journalist Nicholas Lemann proposed that rather than declining, civic activity in the US had assumed different forms. While bowling leagues and many other organizations had declined, others like youth soccer leagues had grown.[10]

And was wrong.

In their 2017 book One Nation After Trump, Thomas E. Mann, Norm Ornstein and E. J. Dionne wrote that the decline of social and civic groups that Putnam documented was a factor in the election of Donald Trump as "many rallied to him out of a yearning for forms of community and solidarity that they sense have been lost."

So like I said they yearn for the ethnostate. Solidarity should be based on class through an explicitly Marxist or anarchist lens, not solidarity in how much they love bashing the fairies.

“People who feel on the margins, who don’t always feel included socially, for whatever reason, that those people are more likely to have higher levels of loneliness,”

So it isn't social media or erosion of civic institutions or any of that made up nonsense, it's just the fact that so many people are still bigoted as hell. That figures. I would suggest them the internet because unlike IRL they have block buttons, adblockers etc to cultivate their own better world.

it's also possible for them to encounter more hatred and bigotry online than they used to in real life (albeit with hopefully less dire consequences).

Just block the bigots? Change platforms? It's ez. This is why headphones always in when I'm outside, best block out the riff-raff wondering the streets on my daily walk. I love technology!

I don't think I'm "just measuring" anything. If you want to plug your ears and pretend that I'm not talking about real problems, that's all fine and dandy. Go ahead about your day and enjoy your dating apps, but social media isn't all roses.

You measure more COVID you get more COVID. Then you go "Oh no! It's on the rise!" and the cycle repeats.

Social media is shit because of corporate control. The early internet free from it was really good.

https://www.noemamag.com/social-media-messed-up-our-kids-now-it-is-making-us-ungovernable/

This just references the book and makes a bunch of extrapolations. Being ungovernable sounds really cool actually. Also something about the "kids born after 1995" and "coddling" and "colleges making kids distorted" set off my dogwhistle alarms off so I went to look this "magazine" up and would you know it: it's run by a think tank funded by a NY slumlord billionaire: https://en.m.wikipedia.org/wiki/Berggruen_Institute

Honestly I expected worse but I wouldn't really take them at their word for opining on how girls these days only know Xanax, twerking, be bisexual and hot chip before examining real material factors for why everyone is so stressed (hint: it's housing and everything being fucking expensive and an exploitative scam and has fuck all to do with technology).