[pjc50]

The early 2000s blog community invented "trackback" for that purpose, but what Nelson didn't forsee was the inevitable problem of a truly open system: spam and other abuse.

[Firadeoclus]

Indeed, what is possible to do in a private or moderated/curated web is quite different from the limits of an open web.

[fulafel]

The built in micropayments would have changed the abuse landscape and need for ads/spam in general.