There is much more to Heroku than managed database and git-based deployments. For instance, recently they have seriously improved the CD experience with Pipelines, Review apps and GitHub sync. They also have pretty seamless integrations with hundreds of providers (email, logging, search, monitoring, ...) in the form of add-ons. You get some basic metrics on your application.

And if security is a concern, or/and you want your dynos to talk to each other, they now have Private Spaces (https://www.heroku.com/private-spaces).

Simply said they are taking the "managed services" experience to a whole new level imo.

Plus, you may not care about that, but they actually have a UI/UX team that can design beautiful AND usable dashboards.

(Note: I don't work at Heroku, just a happy user)