Don't worry about if it's a dumb question, we live for this stuff.
DAO autos mostly exist because of the law enforcement market. There is a.....perception, that a pistol is safer for cops to carry if the trigger is more difficult to pull. Another example of this thinking is that some police departments who issue Glocks put in a heavier connector spring.
The first one I remember was in the early 90s when Beretta released a DAO 92. At the time I was scratching my head, trying to figure out why anyone would think this is a good idea. I was later told, another factor is that in that timeframe, a lot of departments were switching from revolvers to autos, and they wanted to make the feel the same as what they were used to.
Para Ordnance even makes 1911 pistols, which are traditionally single action only, with a DAO system.