Object-relational mapping

Every time I come across things like these, I can't help but think that two trends which have wandered too far off course (SQL and OO) are being shoe-horned back into something which to me seems... odd.

Given that I consider data on-disk and in-memory to be two sides of the same coin, I can only conclude that SQL and OO are going out of their way to be as
different from each other as can be.

Why marry two opposite mindsets?
It makes no sense.