Have anyone noticed that the reason why some persons post go off the topic is because they don't read the entire op writing before they reply to a thread, some persons respond to a thread based on the caution of the topic and that is why we meet up different opinions or suggestions that is not in lines what the OP points of view.
Secondly, when someone have written what you want to write in same thread you have to give off, instead of making a pointless point, I know very well that many users in forum make off topic because what I outlined.
I agree with you but sometimes the title of the thread has nothing to do with the topic, so unfortunately I think sometimes people want to say something about the idea in title but after reading the topic they realize their argument has nothing to do with actual subject of the topic and instead of surrendering or changing their argument they write what they wanted to say despite being off-topic. Mainly because of their laziness in my opinion.
Some people create misleading title of the thread so they can catch the attention of the user that's why its really important for users to read the whole content of the thread so that they will not became a victim of clickbait and they post a nonsense post which is not related to the whole context of the thread.
If we see people committing mistakes and posting off topic on that thread then this is how people look at bad the way how they post. So to avoid being criticized for being out of the topic or post nonsense in a thread we should lets better read the title and the whole sentences written by OP so that we can post accurately and give our best to contribute some good post base on the topic discussed.