Am the furtherest from being an expert, so many caveats:

TIL Wikipedia seems to agree with your assessment. https://en.wikipedia.org/wiki/Columbine_High_School_massacre...

My understanding has long been the FBI profilers determined that spree shooters are begging for help, hoping someone will stop them. I'm pretty sure I got this from interviews in the movie Bowling for Columbine.

So it'd make sense to be alert for warning signs. Like most everything, all the well intentioned anti bullying measures were implemented terribly by noobs and proved counter productive.

But mostly, no one bothered to check to see if any of the remedies were helping.

Well, some measures are known failures. Like zero tolerance policies.

This is a recurring theme. DARE boosted drug use. Promoting abstinence boosted teenage pregnancy. Aggressive pain management led to opioid epidemic. Etc.

Lather, rinse, repeat.