Well, I for one think PostgreSQL is overrated.
The number one reason for why people want NoSQL is horizontal scaling and for that PostgreSQL is terrible, with all available solutions being hacks that don't work.
The number one reason for why people want NoSQL is horizontal scaling and for that PostgreSQL is terrible, with all available solutions being hacks that don't work.
But more common than not, inexperienced devs are using Mongo and similar to store relational data, simply because they were sold the 'MEAN' stack and didn't realize that, while it's easy to get a quick prototype running, a year or two later you eventually need things like transactions and joins, and NoSQL is absolutely the wrong technology most of the time.
Sure MongoDB may not be the best fit for it but my point is more that these are scenarios where horizontal scaling is an important consideration makes more sense for some nosql solutions than for sql solutions. It's not just about single box performance.
Remember, sharding isn't scaling the database. Sharding is admitting your database can't scale so you're offloading the problem to another layer.
I would refer you to an earlier comment:
> In general NoSQL solutions are optimized for certain use-cases at the detriment of others
Your definition of 'right' is absolutely not the only definition of 'right'.
More to the point: there are a lot of problem spaces where the data integrity provided by MongoDB are more than sufficient.
Define tons of data. I'll bet a beer that what you say can fit on a single postgres instance and even be small enough to run fine on a cheapish developer laptop.