So Stack Overflow apparently requires attribution?!??

This has apparently always been the case but it came up recently because they were planning to change the license.

This made me wonder, why? Why should I attribute SO? I certainly don't want attribution for all my time spend on Stack Overflow. Most of the stuff I look up on Stack Overflow is just the same stuff I could find on MDN or MSDN or some reference manual for some library somewhere but it's more work to read the entire manual front to back to grok it than it is to just google it and end up getting pointed to the answer on SO.