For some people 'copy pasting' is hard. Most people don't know how to code and don't want to deal with it.

Additionally I've seen that major media sites use analytics services for tagging and have a way via the tagging tool to inject javascript.. This is a pretty terrible idea but allows the tagging changes to not be coordinated with site changes as usually a different team controls the tagging. Cloudflare would be able to provide another way to inject custom analytics / tracking into pages.