>> But most of the awful SQL I’ve seen over my career hasn’t come from poor mastery of SQL, it’s come from poorly normalized schemas. If you have a properly normalized schema, then you can do a huge amount with very simple SQL. When it’s poorly normalized, you end up with all sorts of strange and inefficient design patterns in your SQL.
This is the crucial insight that has made tons of money for me over the last 3 decades. I have all these trite HHOS jokes about it, like telling people denormalizing from a schema not in a normal form is actually the process of "abnormalization". And then there's generic EAVil, where there's nothing that can't be stored, not that nothing really ever means something, heheh.
For every well designed and useful schema I've seen, there were 999 awful ones. For example a physical data model where the query writer has to use string manipulation for joins is going to result in all kinds of suckage. The developer will conclude NoSql is a perfectly reasonable alternative. Even though a modern RDBMS provides all sorts of nifty features to identify and correct such issues ex-post-facto.
For a relational model to work well there must be an a priori data design performed with significant discipline. This seems like too much like Big Design Up Front for the average developer or technical manager to stomach these days. It is true that a well-designed data collection system will have a simpler data design more amenable to a distributed NoSQL system and will support emergent schema and relations which may be divined via machine learning. It will also make Big Ball Of Mud more convenient to implement, but that's a posteriori observation, heheh, like that damned halting problem...