Because they can’t reach you when there’s a power outage to check that you’re warm. They can’t share boiled water with you when the mains break. They can’t invite you to a meal when you’re lonely.

They can mostly only ever wish you well.

I can only speak to my own experience, but for the last 1 year I have been by myself and my 2 younger daughters in a new town. I work remotely, but also have some very good friends that I can rely on when I need. Those friends are distributed all over the world and while I can call them any time off the day or night, there is a fundamental difference how I feel after a phone/video call to after a conversation over e.g. drinks/dinner. In fact I found that I sometimes avoid calling my friends because the phone call makes me feel lonelier.

So for me online communities can be a great thing, but they can't replace IRL communities, because the interactions make you feel different. I suspect that the social needs that evolution has imprinted on us can't just be fulfilled by online interactions, they require more senses than just hearing and seeing.

You can, but it does replace meaningful irl connection with other humans.

Squigz my guy, you're missing out.