The main issue with MongoDB is that it's so easy to use and seems like it scales, but soon you're invested in it to the point of refactoring being a serious eng

The main issue with MongoDB is that it's so easy to use and seems like it scales, but soon you're invested in it to the point of refactoring being a serious engineering effort, and you're stuck with something that doesn't actually offer real scaling features. So, it's less "nosql vs. sql" and more just "don't use mongodb".