I assume some of you have found some regular posters who essentially never say anything you find worth reading on any thread. If you've blocked them, how strange is it to read threads they're participating in? Is the time saved not having to read or imagine responses worth the hassle of trying to follow what's happening?
When it comes to block/ignore, I find it's more about me than other people. I never block because someone is inessential ... I just scroll past them.
On the other hand, I will block if I find that there is a poster that consistently angers my blood. It doesn't mean that the other poster is in the wrong- sometimes it is them, sometimes it is me, and sometimes it is just an unfortunate combination of them + me; in all cases ignore provides me a time-out and a cooling-off period. The ignore feature, for me, isn't about posts and posters that don't contribute ... it's more about posts or posters that either (a) respond to me in ways I find unproductive, or (b) write things that make me want to respond in ways that are unproductive.*
Normally, I go back and "un"-ignore after a little while. More often than not, if I ignored the person because of something
truly heinous, they've already been site-blocked by that point. OTOH, I can be very goldfish-like and I find that whatever issue originally got me all hot and bothered has dissipated by the time I unignore them.
*In fairness, all of my posts are unproductive. So ... there's that.