It's not like that. A long time ago (2005?) there was an extension for Firefox called "Adblock". Eventually the development of this extension died, and it got f

It's not like that. A long time ago (2005?) there was an extension for Firefox called "Adblock". Eventually the development of this extension died, and it got forked with the name "Adblock Plus" in 2006 or so. The Adblock you're referring to (the Chrome-only extension, right?) was published in 2009. As you can see, Adblock Plus predates it by 3 years or so.