Obviously I'd only be able to say for sure if I was the downvoter but I sometimes observe lighter text on comments which make a reference without calling out the reference. It's similar to using an acronym without defining it, though possibly more confounding if it's a niche enough reference. In this case, I did not get the reference and would have wondered why the parent commenter expected that title to have already been used.

At best, such a comment is referencing something topical which most readers will get (and ostensibly be entertained by); at worst, it's a distracting non sequitur. It generally ties back to a community preference that comments are curiosity-satisfying before entertaining.