> Some companies hire dedicated tech people whose only job is to be oncall, handle alerts, and improve the oncall infrastructure. This role is called ‘DevOps Engineer’ at some companies, SRE (Site Reliability Engineer) at others, and may also be called ‘Operations Engineer.’

I really wish this wasn't stated so matter-of-factly. Neither of these is actually supposed to be true. A lot of times on-call gets stuck on these folks because they're often treated as second class citizens in the softwarescape. There is really great structure for doing these roles right that doesn't involve them making them full time on-call.