Again, I think you're reading a little more into it and I get it due to the contrast of now and previous years, which is where I let some things go on too long.
If there's a thread about a certain topic going on and two people start getting into a war of words (or more specifically, whoever can get the last word), the thread starts shifting toward that (because other people also start chiming in) instead of the original intent of the thread. Now, that doesn't necessarily warrant deletion of anything, but it usually is the starting point where something will happen to push it over. When it does, either myself/or the mods delete that war of words (and sometimes the entire interaction between the two) to get the thread back on topic. If we don't, it spirals out of control.
But disagreements about the topic, honestly, aren't the issue. There are plenty of arguments where two sides are presented and each person battles about whether or not their take on the situation is the correct one, which is obviously fine and it's what makes the threads interesting. No one is expected to agree with everyone else.
There are even moments where it starts to get a little personal, which we usually sit back on because while we're hoping it doesn't bubble over, it sometimes does. Once it does and someone goes a little too far, that's when the posts are removed - when it starts shifting from the argument about the original topic into becoming a little too personal.
Previously, that wasn't addressed years ago and those exchanges derailed the thread because people would start piling on and it would become a mess. The other problem with those exchanges is the fact that it reached a point where things were so ugly, it made it impossible for myself or the mods to punish either person because both people - by that time - had each said some things that really weren't necessary...and on and on it went.
So disagreeing/arguing is fine and nobody has an issue with that, in fact, that's what makes this place so great and it makes the threads more interesting to read/discuss things in. When it starts to get nasty, that's usually the only time any of us get involved. Again, the goal is to moderate as little as possible, but these are obviously the situations we've been trying to at least limit compared to previous years.