I think you are comparing apples and oranges. Heroku is great not just because of its DX, but 1) because it's a subsidiary of Salesforce and I know it won't disappear tomorrow and 2) it has a thriving app ecosystem. It's a real stretch to compare a recent $2.25M seed funded upstart with it and borderline malpractice to suggest running your production workloads on it.
With AWS although you have to pay the premium on egress, you don't pay that until you leave their sandbox; what's more, you can add links into your VPC that sidestep it. If you're just running open source software or a kubes cluster on commodity boxes and you're fine owning all of your operational burden, sure. Use whatever you like. But if you want reliability and good DX, your options get narrower.
Personally, I think that AWS Code Suite and VS/Azure spaces (and GitHub spaces by proxy) are going to be the real challengers in this space. There is a real UX problem to solve but it doesn't mean I want to necessarily use a different platform.
