I'm not sure anyone can label it silly simply because others use the ignore function. Forums, especially popular ones like this one, attract tons of content from members. As a consequence, a lot of reading material is created.
This increases the chances of post duplication or repetitive information being read. On the one hand, a poster can choose to read the same message indefinitely. On the other hand, a poster can decide whether the delivery of the message has become repetitive in nature. If it is the former, a poster may prefer to exert self-tolerance for reading material which has lost its originally. If it is the latter, a poster may wish to filter stale reading material from fresh material.
In my opinion, it is unusual for someone to automatically reads another's written thoughts and immediately say to themselves, "That's it! Enough! Ignore!" I'm fairly certain, with lack of fact, of course, that the decision is made after reading the same post from the same poster, say, Monday, Tuesday, Wednesday, Thursday and deciding on Friday to take action to halt the redundancy. I believe the ignore function is implemented after someone has thought to themselves, "Okay, that's what that poster thinks. Alright, he or she believes this is right. Hmm, this poster is kind of hung up on saying this same thing. Hey look, I haven't read that before. Golly gee whiz, will this poster stop already? It's my umpteenth time reading this poster's comments and who would have thought his or her comment would be the exact same thing yet again. It's been two weeks let's see what that poster is saying... oh same as day one. That was a refreshing discussion on the defensive line, so let's see what that poster is saying now... surprisingly, it's the same thing."
Redundancy is colorblind. Reading the same repetitive positive message can be as exasperating to a reader as reading the same repetitive negative message. Luckily, we are associated with a forum of choice. Just as someone has the opportunity to express their opinion, so does that person have the ability to avoid re-reading the same opinion. Unfortunately, some posters feel this benefit infringes on their right to express themselves. That is an incorrect assumption due to the simple fact that their opinion has already been expressed and read without restriction multiple times. Thankfully, forums such as this allow both the expression of opinion and safeguards against abusing expression of opinion as well.