I have a half-written article about this, but I didn't have any good notion about quantifying the problem so this article is very welcome info to me.

My own angle is that copilot has shifted the incentives around this practice, maybe substantially. Businesses want to get (free tiers of) their paid SaaS endpoints into copilot suggestions - it's a great funnel!

I'd guess that github is as likely as not to become an SEO spam battlefield (like the rest of the web).