This simply isn't true. Many of my closest friendships started online - with people who share the same interest as me, which is rare to find irl. I have since met a handful of online friends in person and they're always as lovely as they were online.
Online friends were very important to me growing up, and still are today.
Everything you’ve said is true, but also you literally cannot replicate in-person interaction. Perhaps one day we will be able to trick our lizard brains with virtual interactions, but we can’t do it at present. There is no replacement for touching, feeling, smelling, and seeing. You can have meaningful relationships online but you are absolutely missing out if you’re only interactions are digital.
But literally no one in this thread is saying otherwise. We’re just saying online friends are real and shouldn’t be demeaned with scare quotes, and also you’re probably missing out if your only interactions are local.
But nor does what you said really answer my question. Online friends are real, and often provide things that local friends can't. No one here is saying they're a substitute for local friends, but that doesn't mean these relationships should be denigrated.
There's a level of human connection and validation that can't be satisfied virtually. We're animals, that contact is important. We wouldn't settle for a virtual significant-other, and by the same token the experience of quality time with buds over extra-curriculars isn't going to be fully replicated in a chat-room, blog message or email.
As recent decades have progressed and more of our lives have gone digital, self reported rates of loneliness, isolation and depression have been skyrocketing. It's sometimes called the Internet Paradox - a technology that is supposed to increase our connection is correlated with increased feelings of isolation.
It's been the subject of study but it's impossible to truly reject the hypothesis due to the ubiquity of the effect - there's no control group. Obviously correlation is not causation, but I think the severity of the effects warrant further thought and investigation.