This is true. When pgSQL, SQLite and MySQL began to support JSON in 2015/2016 a the attractiveness of NoSQL databases - especially - of document stores seemed to diminish somehow.
While it is advisable and recommended it isn't absolutely necessary.
A strong math and tech background will help you get started building the nuts and bolts portion of the project. A vivid sense of curiosity will help to pin-point problem that you can attempt to solve.
Many of the APIs might require you to register a company but they don't require specific domain expertise to get started. Once you have an MVP you can pitch it and gain partners that have domain expertise.
I spotted a small misspelling: “Pass the conversation to someone who has been quite”. I think it should be quiet.