Mostly it's not stuff that would've had a community if it was GPL - it's stuff that would've had a community either way, then Amazon took it and made it proprietary and took the community too.
I don't think it's quite correct to say that Amazon made these projects proprietary. They're perfectly willing to contribute upstream - the issue is they stole the margins from the companies that were trying to offer hosted versions of their products.
IMO this is unfortunate but must be allowed if we want to have truly open licenses.
IMO this is unfortunate but must be allowed if we want to have truly open licenses.