Sometimes you get trolls who come into every thread about an artist that they claim not to like, and they'll have the most posts in the thread. So if you don't have that show ignored content option, the thread really doesn't make sense.
The great thing about being putting people on ignore is that you don't have to see stupid troll threads, or one or two posts in a thread. The great thing about being able to see ignored content is you can make sense of threads dominated by those same troll posters.