Curious why you think this? I've found Relational databases pretty powerful, and learned mongo first.
Where are they really good is reporting. Analysts love rdbms. When I am on an analyst role, I love them them too. As an engineer I find them redundant.
More about domain modeling
https://dev.tasubo.com/2022/07/crash-course-domain-driven-de...
2) In practice having the ability to run reports on your data can be super important and useful.
I'm still confused at the point you're trying to make.