I use Github Actions mostly for automatically publishing my website when I change its content. But I haven't fully set up my build pipeline to my liking. And getting logs and stuff when the pipeline goes sideways isn't very easy right now with Github Actions. If I hosted my own running, at least I could poke around my build environment to see why it failed until I have it running reliably enough to let the cloud handle it.
That's a long-winded way to say: debugging.