It seems that a subset of developers are somehow convinced that adding complexity is a good thing for performance and should be done first, when it should really be a last resort. Their usual rebuttal is "it's scalable" and other buzzword-laden phrases. I wonder if it's a form of "big data envy" or just regular "architecture astronautism".
Honestly, it's the other way around usually; simplicity is scalable. A stateless service talking to a database is fine. You can scale out the service, and scale up the database. It's even easier when you use a cloud provider, their relational database offerings can scale from a wordpress blog's database to enterprise scale, tens of thousands of transactions / second.
The problem is that it's boring, and there's a lot of developers that create work and complexity to make their own jobs interesting.
