Greg Jorgensen writes a fun blog about the common complaints programmers have against relational databases and his responses to them.
Most professional programmers know how it feels to see an amateur, unfamiliar with Knuth or any programming book containing equations, implement their own sort routine. That’s how people who understand relational theory feel when they see a badly-designed database. Relational theory and RDBMSs are old and well-established now, so it’s hard not to think a lot of programmers are willfully ignorant.
I have seen this too: "I don't need a friggin' relational db, just give me a flat file." Sometimes this works, but all too often I see the same programmers adding locking semantics, querying capabilities, indexes, and so on, and I just shake my head.