this article is overly opinionated and narrow-minded.

Many startups use NoSQL. Personally I prefer NoSQL for most use cases. That said I have nothing against SQL itself but I will NEVER go back to using an ORM - They're a dirty hack; always have been and always will be. I'd rather write the SQL by hand.

I love using MongoDB; it's very simple to use. I liked RethinkDB's ReQL even more (even though the company itself had to shut down, the open source project is still great).

The main problem with SQL databases is that the powerful features offered by SQL don't scale; so if you want to build a future-proof system, you have to avoid using certain features like joins; the advantage of NoSQL is that it's built to scale; the constraints are are feature.