Ask HN: Should databases be as smart or stupid as possible?

I made a comment to my coworker that "databases should be as dump as possible and should do as little as possible". He disagreed and said that they should be as smart as possible.

I couldn't backup my opinion but it is just a gut feeling (experience?) that databases should be used as simply stupd data stores with zero logic or code or anything other than data.

Who is right and why?