Comment by rednafi
Relational databases are indeed fun. There's no such thing as schemaless data; the schema either lives in your database or in your code. In the case of Dynamo, the schema lives in your code, determined by your access patterns. The problem is that access patterns change, and this state of extreme denormalization is difficult to adapt to evolving business requirements.
Schemas are a lot easier to modify in code. As a network admin I have spent many hours using solarwinds and directly using SQL to query the database and it is a non-normalized mess of duplicate fields. They have MAC addresses stored in 10 different places in 4 different formats. I think the reason for this is that they simply can't easily change existing tables so have to create new ones.