In those old forums, you couldn’t (easily) bury things the way you can today. We basically handed an incredibly powerful weapon to anyone interested in controlling a narrative - especially so with the centralization of everything.
(I want to be clear that I’m aware old forums could be gamed still, and I’m mostly trying to underscore how messed up I consider upvote/downvote/ratio culture).
We had 'likes' but with actual accounting! For better or worse 'status' could be built with this. Likes, on the other hand, are fleeting
Both systems have perverse incentives, I think the audience - size/shape - matters, and how it all reflects/bounces.
Conspiracy moment: it's harder to fake 'grass roots' things with a smaller/tight knit community, we've been corralled. Once something is as big as Reddit, everything you're seeing is manufactured.
Personally, I think there's truth to the "Dead Internet theory;" less bot focus. Humans maintain responsibility with our choices.
Content must be hosted, and hosting costs money. So how is money going to interact with this system?
Copyright answered that question in the worst possible way. Copyright says that the content itself is the object with monetary value. To support that claim, copyright wraps every piece of content in a box, and says, "Whoever made this shall monopolize its value." In reality, only the box itself can actually behave as a discrete commodity, and no one truly creates content alone: all art is derivative, especially written media. Regardless of reality, copyright demands that we all participate in this delusional game.
So now everyone who hosts content is holding commodities. It's naturally advantageous to exploit the value of your commodities (you can reinvest your profit into actual value), so any business that does that will be more successful than the rest. Anyone who refuses to play the game will simply lose (or be prosecuted). So how do you sell forum posts and memes?
You don't. That doesn't make any sense, remember? You don't actually sell the content: you sell the box. You sell the warehouse. You sell the marketplace. This entire game is predicated on monopoly, so what's the most natural implementation? Vertical integration! Facebook and Twitter don't sell social networks: they sell social walls. What are those walls made of? Incompatibility. The best part is: if anyone tries to build a door into your wall, you get to sue them out of existence! It doesn't matter how broken or exploitative your business model is: if it is based on copyright, then it is guaranteed by law to succeed!
So now you own everyone and everything. How do you make money? By selling them to each other. In other words: advertising.
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But wait, there's more! Copyright answered even more questions: How do you stop people from misrepresenting someone else's work as their own? How do you stop people from sharing your secrets? How do you censor abusive material? The answer is to prosecute fraud and abuse, because those are already illegal. Right? Right? No. That would make too much sense. The real answer is copyright.
When someone operated a forum in the days of yore, they had the opportunity to put up ads and many did. The difference I think is that they were doing so to fund or offset the costs of operating the forum, not as a profit engine above and beyond the cost of keeping the lights on.
That said, greed fed by other monetization models would not have produced the attention economy, and I don't think the evils of other models (dark patterns for subscriptions, planned obselescence, etc) could have come close to the society-wide damage that the attention economy has caused.
I think the centralization is actually a huge contributing factor to the decline in overall health of the internet. We didn't evolve in a way that's compatible with seeing everything that our friends say to any of their other friend groups—we're wired for compartmentalized interactions, not global state.
My favorite period in internet history was the years in which self-hosted phpBB forums dominated the social landscape. We had a diverse set of forums paid for by one or more of their participants, who made the forum available simply because they liked hanging out with the community they were hosting.
Advertising-based social media took all the air from that model and replaced it with the enormous advertising-driven attention economy. Genuine social interaction was largely replaced by vacuous attempts to get "engagement" as the platforms persuaded millions to act in their interests. Vulnerable interactions with persistent communities that allowed real internet friendships to develop gave way to ephemeral rage bait that ruins real life friendships.
I'm not saying that advertising is the root of every single social ill we have today, but it's responsible for its good share of them.