Folks are likely going to say they can't do this "at scale". However, I've been in both the "small shop with Jenkins running on a Dell blade" and also in the "mega-corp with lots of devs everywhere using all kinds of CI pipelines". I think there is merit in what you're saying, but I suggest an addendum.
In both cases, have seen the "CI is down" issues crop up.
There seems to be a middle ground that I have yet to fully do, but have seen folks do and heard it works well:
Make it so folks can deploy their CI pipeline anywhere. In my case, I would create Docker containers that can run the CI pipeline, pipe the output/result to anywhere you want and have it be able to run anywhere.
The goal is that you could deploy it on a VPS somewhere, or on a Dell blade in your closet, or even run it on a dev's machine. The idea is that you want to reliably be able to run the CI steps anywhere without jank while following the full process the same as if it was running on your dedicated job runner solution. Redundancy, if you will.
I think the idea isn't necessarily "Jenkins in your company closet is better" and more of "how easily can you setup your CI pipeline to get your work done?"
In both cases, have seen the "CI is down" issues crop up.
There seems to be a middle ground that I have yet to fully do, but have seen folks do and heard it works well:
Make it so folks can deploy their CI pipeline anywhere. In my case, I would create Docker containers that can run the CI pipeline, pipe the output/result to anywhere you want and have it be able to run anywhere.
The goal is that you could deploy it on a VPS somewhere, or on a Dell blade in your closet, or even run it on a dev's machine. The idea is that you want to reliably be able to run the CI steps anywhere without jank while following the full process the same as if it was running on your dedicated job runner solution. Redundancy, if you will.
I think the idea isn't necessarily "Jenkins in your company closet is better" and more of "how easily can you setup your CI pipeline to get your work done?"