I know for sure NT4 didn't have defragging built in, because I was a Windows server admin back in the primordial soup that was sysadmin'ing in the 90's.

>OCD soothing experience

I've always felt it was a certain kind of person who found amusement in watching a defragger work. I'm absolutely sure that 3rd party tools made sure to incorporate the equivalent blinkenlights to give the impression that their tool did something useful.