There's been quite a few instances when people cry about their topics getting de-railed, when meanwhile it's just two sides arguing which is a functional part of the drama.
A drama normally consists of two sides, the support and the opposition. It's not always topic starter vs. topic subject. Both these sides have their arguments. Now these two sides will argue and fight in order to prove their argument / invalidate the opposing argument. A way of doing this, is too dis-prove the validity of the opposing argument credibility. This often comes in the form of directly attacking members of the opposing argument.
That is not de-railing the topic. So, when you see someone having an argument with another person, bringing up their faults and other things of the sort, that is not de-railing the topic to be focused on them. It is simply an attempt to disprove their credibility in order to support his argument.
tl;dr
"My friends fight your friends" is a valid way of arguing in Drama. Stop calling it de-railment.
