Another daemon for managing control groups

>Right, and car manufacturers in this analogy are distributions and system administrators of large installations. Systemd is not flexible enough as designed. I want to replace the cron-equivalent with another tool, I want to use a different logind, I want to use a different cgroups manager.

Nothing stops you from running your own cron implementation, syslog implementation or eschewing logind entirely. Systemd simply provides a lot of very convenient utilities but they are not mandatory.

The only problem is in the boneheaded single-writer cgroups hierarchy. But that's not entirely a systemd's failure.