However, I don't understand why people are replying to old post...
Exactly my thought. Replying to old post who has probably answer the question a lot of times, is just a waste of time, unless if OP was still not satisfied with the previous answers then everyone is free to add their insights and ideas on the thread. But in all honesty, when you see threads having long pages already, that needs not to prolong the thread anymore but find new threads instead that have not been seen making good replies.
You guys are doing exactly what the discussion is about, not reading previous posts before writing something in a thread.
Please read this:
I had locked this thread, but I thought I'd rather unlock it than create a new one. I just came across another example.
And if you guys aren't talking about this specific thread, then your responses are off-topic and illogical because we are not discussing why people make posts in old threads but we are discussing why people don't read either the OP or previous posts before going ahead and writing a new post which is why most responses in most threads are illogical despite being a bit on-topic.