I wouldn’t lay blame for Heroku’s financial problems at the feet of architecture choices it made customers adopt.

Also, Heroku’s buildpacks were anything but proprietary. They’ve been adopted by a bunch of other products.

What financial problems? They were bought out by another company and tanked. This is the exact reasons why you don't want to tie yourself to proprietary solutions.

Sure, the concept of buildpacks were copied to other platforms (I personally worked on building one of those platforms, Cloud Foundry), but they were a proprietary solution that others adopted for ease of transition off of Heroku, not because it was some great solution to IaC.

This is a bizarrely combative way to discuss this. Can you please instead tell me what you think I should be doing?