Actually they’re still happening (well the new math “mass shootings” where they’ve dropped the number so low it could be a liquor store robbery). But the press has lost interest. Periodically the press beats on a particular type of story until it stops being interesting. It’s like when we were having all those shark attacks in 2001 only it turned out to actually be fewer shark attacks than normal only the press decided to cover them. Then there were all those train derailings, which turn out to happen about every 36 hours whether or not the press is paying attention. Same thing, they really got into the “active shooter” stuff for a while, but they’ve gotten bored.
Yes, this is a reasonable explanation. Further, it speaks to the continued power of the mainstream media. Unfortunately, it still has a powerful hold on us.
ALL of us, myself included.