If you're running one team with all services trusting each other, you don't have problems solved by these things. Whenever you introduce a CNCF component outside core kubernetes, invest time in understanding it and why it does what it does. Nothing is "deploy and forget" and will need to be regularly checked and upgraded, and when issues come up you need some architecture-level of the component to troubleshoot because so many moving parts are there.
So if I can get away writing my own cronjob in 1000 lines rather than installing something from GitHub with a helm chart, I will go with the former option.
(Helm is crap though, but you often won't have much choice).
But setting it up is not a trivial task and often a recipe for disaster.
I've seen a fair share of startups who took too much kool aid and wanted parrot FANG stacks just to discover they are burning tons of money just trying to deploy their first hello world application.