It was becoming clear that Qvitter was the future of the Fediverse. It was being called the Fediverse now, at least by some people, since around May 2012 if I remember our fedi archaeology accurately.
GNU Social / StatusNet was looking old-fashioned and Qvitter was the new and cool web application that looked like Twitter 2013 instead of Twitter 2008. Unfortunately it also broke the Wayback Machine, so today I'm grateful to the sites that retained the old-school UI as their default.
Early on quitter.se seems to have kept old-school the default, so we can see my profile page and that I joined on 2013-07-21.