It can be a source of friction for someone that is just trying to accomplish a specific goal, in this case it might just be to use AWS to go live.
If building a database-backed prototype is your goal, designing a schema is only tangentially related to that goal. Schema design ability can slow you down if you have limited familiarity with SQL and/or the entity relationship model used by RDBMS.
NoSQL allows you to reach that specific goal faster than with an RDBMS by lowering the friction of creating database records and it does it by flipping the schema model from schema-on-write to schema-on-read which is a huge time saver. This made NoSQL great for building prototypes, especially for devs with little or no familiarity with SQL, because it eliminates the upfront effort of designing a schema (that is certain to change anyway) before you can begin to store records in the database.
In other words, the use of a far more familiar language (JavaScript vs. SQL) and the simpler programming model (document-model vs. entity relationship model) is a big part of why MongoDB was able to earn mind share among devs evaluating NoSQLs databases.