The reason this makes sense, at least for Github, is because the only valid reason to run your own action runners is compliance. And if you are doing it for compliance, price doesn't really matter. You don't really have a choice.
If you've been running your runners on your own infra for cost reasons, you're not really that interesting to the Github business.
If you've been running your runners on your own infra for cost reasons, you're not really that interesting to the Github business.