No, it was owner content. Of course, for some sites, like my personal Geocities page, the owner frequently was the sole user too, but the concepts of "one entity who owns the site builds the content" and "third parties visiting the site build the content" are different.
Well, I was referring to the definition of the web 2.0. Wikipedia says:
Web 2.0, [...] refers to World Wide Web websites that emphasize user-generated content [...][1]
So while in the beginning most users were also authors, there was a time between when there were a lot of websites which served content, but didn't let users add theirs. At that time guestbooks were to only place you could add content to someone elses website. To some degree message boards where the start of the Web 2.0.
