Hiring someone to exclusively babysit a Jenkins instance is incredibly expensive. Paying for Travis CI/Codeship/Gitlab CI is really cheap in comparison. Having developers fill out purchasing orders and waiting for software or hardware is very expensive.
I like to call it the "IntelliJ test", can I requisition IntelliJ ($499) and have it the same day (week? month?) or is the company going to flinch, hem and haw at the absolutely inconsequential price of the software in comparison to the expensive developer time they're paying for.