I doubt that. Someone who doesn't like reading wouldn't think of "spoiling a book" as a prank category that comes to mind or understands it to be a serious upset rather than just slightly annoying. Also, they'd likely feel that going to a bookstore and shouting things relating to a book serious is "cringe" or whatever you want to call it, if they aren't the type to even go to a bookstore in the first place.
All it takes is one person to go "I did this" and then the others have a good troll/joke to use. Doesn't take a lot of effort and people were more outgoing back then.
I actually liked reading and I was a nerdy kid. To be clear, I never actively participated in the spoiler stuff, just read about the reactions.
I mean, keep in mind I was fourteen when this happened, and fourteen year old boys are very often assholes and I was sadly not an exception to this.
I guess I just found it funny how much of a reaction people had with it. I liked the Harry Potter books too, I was reading them like every other fourteen year old was, and the plot being spoiled for me didn't really bother me very much, cuz, you know, it's just a book. Some people really got upset.
Again, definitely a dick move to do that, and a dick move for me to find it amusing. Kids are douchebags.