Will I have to patch machines, keep packages updated, deal with SSL certs, maintain action runner infra, deal with billing for the machines, add monitoring, alerts, logging, etc
No, I don't want to be in the business of running my own Github clone. That's what I pay Github for.
Why do you pay salary to employees to buy food when you can just run a farm next to the office and save money by operating the farm and giving the employees food directly? You'd save money by not having to pay as high of salaries, and farms don't even need 24/7 devops teams.
Don't you think the farm example was a bit too extreme for it to make sense? A tech company probably does not have expertise in farming but devOps is something they already know how to do and can easily manage it in-house. Also how fast do you think farms produce food that you can drip feed it to employees constantly