If only there are tools for sharding PostgreSQL. Easy sharding is still a major weakness in relational databases.
I used to complain about the lack of "out-of-the-box" sharding middleware myself, but came to realize that this is really something that belongs in the application layer for all but the most trivial use-cases.
However, there is no reason why full-stack frameworks such as Django and Rails couldn't grow meaningful sharding support.
But at least it gave me starting point, which is already more than most other ORMs can offer.