And besides, AWS has a stable API and a set of CLI tools to actually manage everything in the cloud without button pushing.
I am 29 now. Used Jenkins about 5 years ago because I couldn't find a much better alternative for a single-developer workflow, but it's a glorious pile of buttons that has 0 consistency and/or an API.
Secondly, to your point, there you go: https://stackoverflow.com/questions/17716242/creating-user-i... I'm pretty sure that the reason there is no REST API for it is because you're supposed to be using your favorite back-end (LDAP, AD, etc.), with which Jenkins can integrate.
It's quite disingenuous to complain about the Jenkins APIs, there are a lot of them. They're not perfect or designed necessarily like something you'd design in 2020, but they are there.
And they also look better.
For god’s sake, you could even use GitLab today. What does Jenkins give you? What is there to defend?