@Krumple,
You (or rather Pangloss, who was the one talking about the thread being hi-jacked) don't have to blanket ignore someone.
You can simply vote their post down on a particular thread, and YOU will not see it.
Threads here are, in my view, often hi-jacked by the same small group of people.
(Others would say the same, but be referring to a different group, of course!)
These people can't really do any real harm themselves, it is easy for lots of us to simply scroll past their posts. or have them on ignore..whatever floats your boat.
However, often people get very irritated by them and respond. This is really when a whole thread can be de-railed...when it becomes masses of postings between a few people, on things not pertaining to the thread, and frequently in the form of ever-increasing personal insults.
Once this has happened, people often give up and stop posting on what had been a really interesting discussion.
This is when I really wish people would use the aids to ignoring given them...if they cannot simply scroll past.
I am not saying you don't have the ability to do that without artificial aids, but lots of folk seem not to have, and this de-railing can be quite a destructive thing when it happens.
With very little modding here, there's nobody to stop this process except us.