Heroku seemed like it was going to be the future back then. Every time I find myself struggling to understand some nonsense in Azure I dream of the simpler future we lost.
They got painfully expensive and then acquired. I still remember the arguments with clients and finally went all in AWS ECS, which is still quite pricey but clients seem to complain less about the Amazon bill then they did about Heroku.
Other than the pricing, for something built for simplicity, i always found their config method bit weird. Maybe it's just me b/c I first learned the aws stack, and got tired of managing EKS
Yeah I don't see a reason to use k8s if not on cloud, and k8s on cloud is even more complex. Compose is still the right size for one box, that one command does all was really nice to have