It seems that most of those concerns are not alleviated by using GitHub or GitLab SaaS: "figure out the software you want to use" (you still have to choose the platform), "figure out authentication" (you still have to link your SSO with the platform), "continuous integration systems (...) or production servers that pull from your Git repos, you're going to need to figure out how to connect all of this to the Git server" (you still have to do this), "Git version compatibility" (still a concern, unless you only write code from a browser).
I might be extremely naive in thinking this, but all the listed concerns on that blog post seem rather straightforward to account for. Is there a hidden complexity that I'm just not seeing?
What a weird list.