I personally agree with your sentiment bro,  most of this similar thread are mostly not the same, they might look alike because it all boils down to the same ends results, so the best thing to do just as you rightfully said is to tell them to lock the thread, and let that issue be discussed in the main thread, but having a serious issue with when  something like that occurs, is the least of my problem.

And lastly, the op of this thread should understand that not everyone are the same, people behave and think  differently, because we all have eyes that we use in looking, but we sees differently, so getting upset over something that can be easily corrected when pointing it out should be a no no, because I believe that you have a more bigger problem aside that, unless you are sad or grumpy on how life have been treating you, so you just decide to transfer that aggression on someone else, if not, I see no need getting upset.