Hey John, I'm sorry for answering this late. I haven't figured out a way to get notified about replies to my comments so here I am, backtracking what I have commented within the last few days. Sorry!
I'm referring to issues on open source projects hosted on GitLab.com so I think what this is about is out of your scope in some way? Also I've noticed that my initial comment is probably biased heavily by the projects I tend to follow on GitHub and GitLab. Gigantic projects (e.g. Inkscape vs. PyTorch) aren't different for me due to the active communities and after a second thought I have to admit that a lot of projects I follow and software I work with (PyTorch, Tensorflow as well as smaller ones like Potree, pyAIS, MIDI2LR) seem to live on GitHub. That's how some projects I did end up being on GitHub as well. On the other side me and my working group believe in Open Source so larger projects tend to end up on GitLab.
I'm not even sure if it helps but I didn't want to leave it "unanswered".