Yeah I started using GitLab for the same reason and also that FSF "approved" of its CE version. But doesn't hosting private repos on GitLab and using public repos on GitHub just give GitHub that much more monetizable value?
Also if we're being honest, despite Gitlab being the #2 platform, you're going to get less contributions than on Github as people just aren't going to want to sign into a second service. Now most of my public projects are like "I made this, I put it here to show off, and use it if you like" so if people _don't_ use it, it's no big deal for me, but if you're in it for revenue or clout or just like seeing usage numbers going up, it's clearly not the optimal choice.