I haven't put any poster in my Ignore List yet. I can skip, skim, scan posts on my own.
Maybe we need a better analogy.
I don't enjoy stepping in pet feces (especially in a climate where I'm usually barefoot). If I knew that there wasn't any on the ground where I walk, then I wouldn't have to keep an eye out for those unpleasant surprises. You can't ignore them because they ruin your day and can ruin the days of others.
I don't like seeing litter on the streets of our neighborhood. I don't spend my days chasing around with a broom and a trash can, but if I see a piece of litter blowing around then I'll pick it up and throw it in the trash. It makes me feel good to do a little bit toward cleaning things up and making a more pleasant environment. I wasn't responsible for creating the problem but I helped fix it.
I know I could ignore posts by objectionable posters. (Remember the "Asian male porn" spammer?) But they make me grumpy and they litter the board.
Don't threads seem disjointed when you can't see stuff posted by your ignored posters, especially if they are prodigious posters with a post in almost every thread?
On the other hand, a lot of our threads zigzag around the original topic, so not seeing some posts may not make much difference. And one can see posts by ignorees when they are quoted by non-ignored posters.
I suggest that you try it. Put someone on your ignore list and see how the board experience changes for you. You can always take them off the ignore list again.
But I suspect that you won't miss anything, any more than you "miss" the inital post of a spammer who was banned before you got on the board that morning, or any more than we "miss" H0cus. Maybe once in a while you'll be curious about something the ignoree said and you'll click on the "View Post" button that's on the upper right of their post (or some other poster will quote it). But after two or three of those you realize that's why you put them on the ignore list in the first place.
It makes the board a faster read, I don't feel grumpy from trying to dodge all the obstacles or pick up all the litter, and I don't have to endure unpleasant people. Sounds a lot like the reasons I ER'd in the first place...