There are ways to ensure that people are people on the internet though. Not good ways but there are ways.

You could for example limit users to those that log in with electronic id's issued by a government or other organisation that you trust to assert that the user is human and then force real names or a single user name for that e-id.

But when bots do a lot of things better than humans, including comment, answer questions, make jokes, say romantic things, etc. many would start to prefer them to humans in their online communities, and give them even more social capital.

This already happened in other areas of life. Both fathers and mothers now neglect their own children and elderly parents so they can work for corporations. They often prefer this and find meaning in climbing the corporate ladder. Eventually, their own labor will be rendered obsolete, but for now they're in a race to the bottom to work harder and neglect their family even more. They even stick them in nursing homes.

Also, you no longer want to ask people for directions, you use Google Maps. You no longer ask your parents, teachers or libraries when you can just look it up online with no judgment.

Finally, look at industries like Wall Street trading. It used to be a bunch of guys in a pit. You'd call up your broker or whatever. Now everything is automated with bots. Everyone prefers bots. They make up the bulk of trading with real capital. These bots are are working for corporations, which employ less and less humans.

So the present is already a bunch of corporations owning bots and bots creating content for other bots. In the finance industry. Now how different is a bunch of text generation online? I think the human contributions will be vanishingly small in most communities.

The question is ... what is this all for? Dropping demand for human services is a byproduct of making things more and more efficient...

Exactly, it's not for us at all.

This tech is not a quality of life enhancer at all, it's our competition as a species...but then again if we are really this stupid maybe we (well, you lot) deserve to die at your robot overlords hands.

You don't have to force it either. It could be an option. And if it was well-designed, it could probably be made so that it was only pseudo-identification, e.g. where the site knows you're a real person, but not which one, and where the issuer knows you have an account on the site, but not which one.

Obviously you need good ai swarms to combat the bad ones

And here we have the early side-plot describing the end of the internet in the book Fall by Neal Stephenson.