We grow up. At a younger age you are willing to put up with asymmetrical relationships, mostly because you don’t realize they are asymmetrical. You just start seeing them for what they are as you age.
You just have to accept that socializing won't feel the same or have the same function in your life. You choose how and how much to value what you make of it.
Most of these fears are absurd. Why can't you just go outside and talk to anyone you want? If your answers are along the lines of "it's rude" or more honestly "I am awkward", then congratulations you just figured out what's holding you back.
Everything we're doing here online can be (and is!) done offline. It requires some acceptance of discomfort and recognition that you won't be so precious about IRL conversations anymore. It will become as mindless/mindful as you can handle, but opportunities are always everywhere to make friends.
I think we're talking past each other here. You and the article say "we", but it sounds more like "you" and everyone else that has not found new reasons to socialize.
I do tangentially agree there may be an answer why the old reasons aren't good enough anymore, but that doesn't mean there isn't as much value.
If anything there's more value (to me) now that I have a better grip on why I socialize as an adult. It became more nuanced with my lifestyle changes. I stopped needing friends and started wanting them. I keep the ones I have for their perspectives on life. I have far less in common with my adult friends than I ever did when I was younger. I deliberately select for that. It helps me find balance.
Definitely not universally true. I was a big introvert in high school and college, but now as an adult I am way more extraverted and have more friends than ever.