Yes there was Flickr but you could discover photos. Thing is, Flickr is still there and you can still use it. What's clear from this is that Flickr didn't (and doesn't) cover what is the use case for most people: sharing photos with a limited group of friends and family.
Technorati? Honestly, I think this is an example of living inside a very small bubble. I'd honestly never heard of Technorati until long after it had waned.
I don't agree that the monetization of the Web has degraded the value (to the user) of links on sites other than links on sites aren't the primary discovery mechanism like they used to be, which is actually a good thing (IMHO).
> In the early part of this century, if you made a service that let users create or share content, the expectation was that they could easily download a full-fidelity copy of their data, or import that data into other competitive services, with no restrictions
This is only true to a limited extent IMHO. The primary services for creating information 10+ years ago were email providers. Because Web-based mail was a latecomer, services like Yahoo Mail and Hotmail grew up in an era where many people used Outlook, Thunderbird and other desktop email clients so they had to support POP3 (and later IMAP) and you could use those services to export your mail.
But that isn't the same as designing your services for interoperability. That was an unintended consequence.
As the idea of "your mail, everywhere (you have an Internet connection)" became dominant, so did Webmail. POP3/IMAP became less important.
Again, I consider this a net positive change.
> In the early days of the social web, there was a broad expectation that regular people might own their own identities by having their own websites
This I disagree with. Having your own domain and Website 10+ years ago was pretty unusual. Administering your own site is not easy, particularly as malware became more prevalent. This has declined because no one wants to run their own Website (or email server for that matter) because it's a crazy amount of effort for very little real gain.
The only real problem I see with the present state of the Web is that Facebook wants to own all your data. It wants to be your identity. It wants to be your Internet. That's bad. It's bad for the Web and bad for consumers. But honestly, I don't see it coming to pass. Facebook is just as susceptible to disruption as so many behemoths that have come (and gone) before it.
10+ years ago Microsoft dominated your computing environment. Many couldn't envision a future that would break free of this grasp. In a few short years Microsoft has diminished their control of your computing experience in ways few could've predicted. I'll just leave this as an example of the danger of extrapolation: