And metrics and growth was driven by the new ability to make discussions out of posted content (i.e. Web 2.0)

I feel like you have that exactly backwards? To me it was a shift in roles in the old field of dreams storyline. I.e. "if you build it, they will come".

In Web 1.0, you posted content and an audience came. In Web 2.0, you tried to open an empty field and commenters came and played with each other.

If anything, what happened next was a sort of halfway reversion, as the platforms tried to stratify and monetize two types of user. A subset who were the Web 2.0 contributors and another tier of more passive consumers. I think a lot of the "likes" stuff was also less about self-moderating channels and more about making passive users feel like they're engaging without actually having to contribute anything substantive.

There was plenty of discussion online prior to XmlHttpRequests, see vBulletin, Fark, Digg, etc. The only thing new about “Web 2.0” was a page refresh not being needed after an http request.

No, metrics and growth always existed and could be measured there wasn’t some technological breakthrough to enable that with Web 2.0. They, Facebook, decided to use it as their guiding principle. They decided to force the feed on their users. They knew their users had no real alternative and the value they had built with getting everyone on the network itself.

If anything, their move was anti-web 2.0. As they moved forum and blogs and news, pretty much all open and accessible content into their walled garden. Even the famous quote “know what’s cooler than being a millionaire? Being a billionaire.” Or however it goes, is a ruthless capitalist telling Zuck he needs to wake up and realized how valuable this thing he’s built really could be.

Carry on if you want but I think you’re very much the one that gets it backwards? Do you remember how it all transpired or are you too young to really understand what it was and what Web 2.0 really was about?

uhh what? Social media has been a thing since the very inception of the internet. What did feel like a massive transition is the massive prevalence of corporatized social media.

I feel like if you asked the a random warez group in 2010 if they would purposely make a "business" friendly version of themselves on a social media site owned by Microsoft they would have laughed in my faces.