I think there should be some incentive for that, like make those kinds of comments a spotlight or something. Maybe make a community called “late replies” that showcases the best such replies, or have a rule saying they grant free karma (in Reddit’s case).
I kudos answers constantly. Half the time it’s my own, which means my account knew the answer and posted it, but I remember none of this.
I may be multiple personalities, and I may not even be the smart one.