Is this a bit? The median CS undergrad has zero experience with large & successful software systems in the real world. Of course they wouldn't understand!
Yeah - in fact, this is probably a great example of stuff you don't learn in class that gets really clear in the real world:) Operational concerns trump a lot of other things, and shoving everything you can into 1 database technology is so much better to manage that it covers a lot of suboptimal fit.