As the article mentions, the name was already in decline well before Glitter was a factor. It just belongs to a certain tradition of English names that are slowly disappearing. Some of them disappear because they now sound pompous (like Harold), some because they sound too “vulgar” (which imho is the case for Gary). A lot of names survived only thanks to rigid traditions (“firstborn will have the grandparent’s name”) that have been slowly dismantled for a couple of generations.

If you really want to talk “infamous” names, you should pick the two classic examples: Adolf and Benito.