Event stories imo don't really have "creative integrity" (i can't really phrase what i mean but that's the closest), the way a legendary multi-issue run by a really good writer/artist team does.
I would say even ongoing series struggle with this "creative integrity", because of the over-abundance of content + the lack of quality control of said content.
Harry Potter would not be the same story if it were interspersed with shitty chapters written by other writers, some good, some bad, etc.
If everything that happened, really happened in continuity, then there's little dramatic resonance or emotional believability behind any story. It's literally crisis number 7,325. If everything happened, think about how many deaths and explosions and rebirths they've been a part of. After a certain point its just not believable or special anymore. Heck even TV shows that go longer than like 4 or 5 seasons suffer from this, to say nothing of comic books.
I love, for instance, Grant Morrison's X-Men run... but if you think about ALL the X-Men continuity, the story feels a lot less special. It's just one of a thousand different "wild swings" that happens every year. Within a year half of it was gone.
It's because of this that I don't even follow continuities anymore. I just wait until a writer's run starts gaining fan + critical buzz, then catch up on just that run. As long as there's a healthy amount of issues in that run, it ends up feeling more or less like a filling story.