as a total hobbyist: why?
deploying a django app with zappa is extremely painless... its only issue is that you still need an SQL backend, as DynamoDB isn't really an option unless you want to kiss most of djangos values goodbye.
that would've been my take why you'd want to use flask... because there is very little value in django if you remove models, caching, authentication, permissions and more (that can't be used without external infrastructure) from the equation.