There are two primary problems with software today:
1. Full-Stack Developer: everywhere full-stack developers are sought. No-one seems to think that the full-stack developers are commonly jack-of-all-trades and masters of none. 20+ years' ago it used to be that the full-stack developer was the old programmer who had become a master of all the various areas within programming. Now, a full-stack programmer is someone given the task (and responsibility) of programming the entire stack.
I can see why the developers chose the DBs that they did. They picked the ones that are relatively easy to implement and are reasonably fast. Oracle is not at all easy to master but it is a superb database. This does not fit the current paradigm.
Nowadays, the full-stack developer is given the responsibility for everything and the DBAs are given the task of making the developer-designed database and entity-framework spaghetti code perform better (well, perform).