I recall that theory being promoted quite a bit in the last several years. To discourage copycat mass killers, experts suggested not sharing their names or reporting extensively in the news media. IIRC, the Sandy Hook shooter had a spreadsheet or database on his personal computer listing all the previous mass murderers, listing their weapons, number of people killed, etc. These maniacs actually follow the example of previous killers, try to learn from them and seek to kill more people than anyone before. It's part of the reason why many plan these killing sprees ahead of time.
The notes of the Sandy Hook killer and others, IIRC, also revealed a desire for these killers to get extensive news media coverage. That public attention is a very big goal for many. If you go back to visit some threads here at WS for those mass killers back then, a lot of members posting here didn't use the name of the killers in discussion.