In the close menu there is an option for
off topic because > Questions about software development are off-topic here, but can be asked on Stack Overflow.
Why aren't these automatically moved to Stack Overflow?
Basically because Stack Overflow has very specific rules about asking software development questions and most such questions posted on AD are written in a way which would get them closed/rejected quickly on SO if we just migrate them over. It's easier if the OP familiarizes themself with the rules, maybe searches for existing questions relating to the same topic, and then asks a specific question on SO.