Github being a single pane of glass for developers with a single login is pretty powerful. Github hosting the runners is also pretty useful, ask anyone who has had to actually manage/scale them what their opinion is about Jenkins is. Being a "Jenkins Farmer" is a thankless job that means a lot of on-call work to fix the build system in the middle of the night at 2am on a Sunday. Paying a small monthly fee is absolutely worth it to rescue the morale of your infra/platform/devops/sre team.

Nothing kills morale faster than wrenching on the unreliable piece of infrastructure everyone hates. Every time I see an alert in slack github is having issues with actions (again) all I think is, "I'm glad that isn't me" and go about my day

Yeah, it seems like a half-assed version of what Jenkins and other tools have been doing for ages. Not that Jenkins is some magical wonderful tool, but I still haven't found a reasonable way to test my actions outside of running them on real Github.