Jenkins is cron with bells and whistles. The result is a pile of plugins to capture all the dimensions of complexity you are likely to otherwise bury in the shell script but want them easier to point and click at. I'll hate on jenkins with the rest of them, but entropy is gonna grow and Jenkins isn't gonna say "no, you can't do that here". I deal with multiple tools where if tried to make fun about how low the jenkins plugin install starts are, you'd know exactly where I work. Once I've calmed down from working on CI I can appreciate Jenkins' attempts to manage all of it.

Any CI product play has to differentiate in a way that makes you dependent on them. Sure it can be superficially nicer when staying inside the guard rails, but in the age of docker why has the number of ways I configure running boring shell scripts gone UP? Because they need me unable to use a lunch break to say "fuck you I don't need the integrations you reserve exclusively for your CI" and port all the jobs back to cron.

And that's why jenkins is king.