There’s really no point in pinning blame yet. It’s the same mentality that led to knee-jerkedly blaming Liverpool supporters post-Hillsboro until the Taylor Report came out and absolved them.
In the recent Ajax match, yes it was an Ajax supporter who was the pitch invader, but it could easily have been an AZ or a Den Haag or Feyenoord supporter, on a different day, in a different match.
There are many issues for hooliganism and there is no such thing as one club or one faction that is worse than any other, on any given day. in UEFA, they are lucky enough that violence has been muted down to racial slurs. mostly. and any club’s supporters are as capable of that as any others. So pointing blame at one set of fans does what? doesn’t bring back the dead. doesn’t heal the injured. doesn’t fix the image of that tragic day. it does, however, allow the governing body(ies) to say “oh, it was just THOSE fans” and not have to deal with the issue.