For me, it was the events started feeding directly into the next event, without even a few months of "that was great, let's get back to the regular stories" business.
In DC's case, they really had their events under control for most of the 90's. Events would run for a couple of months, sometimes three, get wrapped up, and that would be IT for at least 6 months. Sometimes there'd be two events during a year, but those would typically be one legit "interrupting all the titles" crossover (e.g. Invasion), along with one crazy event running through the summer Annuals (e.g. JLApe or Armageddon 2001). In any event, when those stories were done, they were d-o-n-e done. There weren't epilogues teasing the even bigger menace lurking behind the just-defeated menace. There weren't double-page spreads advertising coming plots over the next year (half of which would never happen because of editorial changes). There were no last-second "wtf" moments. There were changes to the titles, deaths to be mourned, and new characters to be exploited, sure, but the event was OVER.
Then, somewhere around GL: Rebirth, it was decided that every gorram event had to lead into the next one. To which I say, "F that noise. F it with a rusty spork."
So yeah, I kind of blame Johns for this.