While it might seem that the world has moved on, the core developer experience on Heroku is still pretty awesome.
One aspect that I loved, loved on my recent project was the ability to seamlessly clone a Postgres database. I would set up a follower, have it suck in all the data from the leader, then stop the following and voila, I'd have a copy, e.g. for debugging production issues. All that with a few simple CLI commands.
I think Heroku is still a great fit for monoliths that only need a few dependencies like a database and Redis.
Once you need more, there's the Heroku marketplace, and yes, you have an add-on for everything but the fees add up quickly. And while an enterprise customer might not even notice four to five figure monthly bills, a scrappy boot-strapped startup or a solo developer surely will.