Most use it so that the board is readable. My Ignore List has the following from the last few years: Death, Frank, Quest4twelve, ND521, Nocalirish, FinnMcCool, ND1IRISH. These are low-I.Q., N.P.C. buffoons who end up driving massive "I-know-you-are-but-what-am-I" threads of worthless whining and having-the-last-word addictions. You lose visibility of threads and posts worth engaging with - even in an ugly way - if the garbage from these trolls is spread across your Open Forum pages.
I don't personally have Tryrone blocked, but in Baron's case, the guy made direct threats about trying to dox him. I don't blame him for sending him off to the phantom zone.