I think the reasons mentioned in the article are to be taken seriously (unlike some of the other commenters here). Historically, Microsoft has shown itself as "not an ally to Open Source" to put it mildly. And there is a real tie-in to Github-the-platform (issues, workflows, etc) despite the fact that git repos themselves can be migrated away trivially (by design).
Having said that, the alternatives they mention aren't realistic. Precisely those things that make GitHub dangerous, are the things that make it worth choosing. In particular: network effects, issue tracking and PRs.
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