That's not what I remember. Back in the days when people started implementing dvcs git was just much faster than everyone else (that was in fact the reason why

That's not what I remember. Back in the days when people started implementing dvcs git was just much faster than everyone else (that was in fact the reason why Linus wrote it). Once the kernel was using it, its mindshare just grew much faster because of the publicity this implied. In other words it was largely a case of "if the kernel devs are using it it must be good". When GitHub and all the other hosting services started many still had mercurial or other dvcs (launchpad was bzr for example), but by that time the ship had sailed already I would argue.