If you’re spinning up a personal CMS, great. Have fun, you’ll learn a lot.
But once you’re dealing with multiple users (tens or hundreds) it’s a different problem. How confident are you writing auth and password reset flows? How sure are you that the AI got it right? How solid is your approach to roles and permissions? Are you implementing 2FA? Supporting drafts, scheduled publishing, editorial workflows? Now you are also tech support writing the infrastructure as issues come in.
That's a very different scenario.
So please, if you're going to make sweeping statements on a CMS, please clarify if you're talking about a solo site owner situation or a multi-user setup.