No offense, I think people are crazy to rely on a stack they can easily make themselves vs. a series B startup. It's not that difficult to build and deploy full stack apps on your own server.
The very nature of an innovative idea is that few people see it.
I have a bunch of apps on Vercel right now and zero worry that I will be able to deploy them somewhere else should they drop out for whatever reason. They are just Node/React apps.
I pushed a new proof of concept to Github yesterday and deployed it in literally 3 clicks on Vercel.
Please show how to do this with AWS.
Then take a look at the features like preview deployments, CDN, environment variables etc. Does your solution cover all of them with the same ease?
I think people are crazy to accept abstraction on the machine layer but keep reinventing the wheel for the infra in the middle. These services let's you focus on the actual product.
In the meantime you get faster, free hosting, better builds and spend zero time on ops.