I strongly disagree with you on that statement.
SQL databases are old, but definitely not outdated. Most business data is inherently relational. Every web application has relations between Products, Categories, Orders, Customers, Payments, Addresses and so on. You generally want strong schemas, relational consistency, ACID compliance and so on to keep your data consistent.
Sure, schemaless databases are “flexible”, but that just means you’re going to have to protect the data consistency yourself. And deal with the consequences if (or when) you fail.
It’s no surprise that new NoSQL like databases which function like relational databases are gaining traction. CockroachDB for example is compatible with PostgreSQL and is much easier to scale, but is lacking in both features and performance.
Also, it’s not like we can offer a NoSQL database and have “NoSQL” covered. Some want a key-value store (e.g. Redis), some want a document store (e.g. MongoDB), some want a column store (e.g. Cassandra) and some want something else entirely. You can’t offer one type of NoSQL database and satisfy everyone.
Sure, the Facebooks and the Netflixes of the world have NoSQL databases. But they also have thousands of engineers, and datacenters all across the globe. Most websites don’t have such needs. Just because Netflix does it doesn’t mean you should too.