It is combination of no innovation and the pricing model. The pricing model only ever made sense for hosting RoR applications due to particular sub-optimal perf

It is combination of no innovation and the pricing model. The pricing model only ever made sense for hosting RoR applications due to particular sub-optimal performance characteristics of RoR at the time. Ten years ago you could get one meaningful VM instance for the price of one dyno and host anything you want on that but you had to somehow make that work. Today the price of one heroku dyno buys you one or two VMs where you just deploy docker compose or whatever (as long as it does not involve etcd, because then you are outside of the "free/cheap VM instance" category) and are done with it.