"Some" people need the ignore because they really don't want to hear another point of view, it's that simple. Instead they prefer to have others post that will agree with whatever "their" ideology or opinion is.

"Some" people use the ignore because for some reason another member may be triggering them too.

A lot depends on where someone may be in their challenge if they are struggling with a MI and want to interact but just need to feel safe while doing so.