Its inertia, its just not a priority to move them over
Surprisingly not as much as I'd thought when they took it over. They just never adjusted pricing to remain competitive. The experience is still some of the best you can get for RoR apps. But nobody in their right mind deploying a new application today would look at their insane 10 year old dyno pricing and be like - yup - reasonable
I think even multiple buildpacks at once only came a couple years after acquisition.
Possibly they were in the pipeline before acquisition, sure.
But I'd agree, heroku is still a better DX than almost any competitors, although it's features and pricing have really stagnated. So better DX as long as you don't need any features it doens't have. But it hasn't really been 'ruined' in any way, it just started appearing frozen in amber some years ago.
The new 'fir' platform is promissing, before that I didn't really know that any actual development was taking place in heroku, but it's a big move, modernizing things and setting the stage for more. Including slightly improved resource-to-pricing options. We'll see if it all works out...
also, you used replit for the frontend deployment? or frontend and some backend?
thanks - just super interesting as I'm in the space and feedback/real cases are really useful