I believe my point still stands given your clarification.
AppSync is not the same as Firebase/Graphcool/Meteor but it’s a comparable level of easy-to-use, flexibility. What would you compare it too in non-AWS otherwise?
Yes I agree AppSync is probably faster to get started with than building everything from scratch.
Firebase/Graphcool are probably easier to use though.
It’s true that if you have already have DynamoDB tables for a REST API than migrating to AppSync is a good incremental step.
I’ve built my own stack similar to AppSync just using Serverless, apollo-server-lambda, Apollo and pusher.com. I’ve used it for a large SaaS software that is already 5 years old and will likely go on for at least 5 more years.