Define popularity? SVN was still the majority platform because Sourceforge and Google Code were the most popular publicly accessible project hosting platforms. A lot of the self-hosted projects were still on CVS repos, often without anonymous access, so you'd just get tarballs of the source code with releases as a non-contributor. My memory is definitely that github adoption drove git adoption by basically its code first approach being more appealing to developers than Sourceforge/Google Code's project first approach.
Later on stuff like git-flow came along which also helped people have a process to migrate to (even if it's poorly suited for the development patterns software projects were already migrating to at the time).
Later on stuff like git-flow came along which also helped people have a process to migrate to (even if it's poorly suited for the development patterns software projects were already migrating to at the time).