We[1] have seen a fair number of requests for managed services as devs claim that "we don't have the time or skills to maintain these open source components" (quoting verbatim from a request on Intercom). I don't think this is about having open source substitutes in all the cases. Personally not a fan of how/where the build vs. buy debate is playing out here.
"we don't have the time or skills to maintain these open source components" translates to "we don't want to install a monitoring solution that restarts a service when it fails, or think about design in regard to component failure".
It's such a poor argument. I was a developer long before AWS appeared and I've used so many open sources packages that were profoundly reliable. In many cases it just takes a daemon restart. And while it's not exciting to set up some of that stuff, it's far more tolerable than writing a CloudFormation template.
[1]: https://hasura.io