[zzzcpan]

I don't think I ever heard a good technical reason to use a traditional RDBMS. And as a default choice it is not a very good one, when something distributed can deliver an easy to maintain resilient solution pretty much out of the box.

[SOLAR_FIELDS]

I'm sure many can be produced, but the first off of the top of my head is accessibility for quasi-developers. If you ever want to hire some analyst roles you are going to find that it's a lot easier to get people that have at least some familiarity with SQL instead of having to train them on whatever custom NoSQL flavor you are using.

Of course you could solve that by having an ETL process dump your stuff into SQL (we keep our stuff in Cassandra and dump it into SQL for analysis), but that's another ETL you need to keep track of and in our case we use a quite complex data model and the ETL only supports a subset of it.

Another one just off the top of my head is joins. Some data is just inherently better suited in normal form.