I've found that a lot of junior developers are so scared of making a wrong database schema in SQL that they rather pick a schemaless database. Which of course if you're not careful leads to multiple conflicting ad-hoc implicit schemas in your NoSQL database. I.e. maintenance headaches.

Ideally do a meaningful MVP schema and then iterate on it. Schema migrations can be done. And it saves you so many headaches later on to have a reliable schema for your data.