I'm gonna try to say my opinion in a way that doesn't sound as antagonistic as some other responses...
I feel like it is a problem, but not as big as a lot of people seem to make it out to be. Admittedly yeah, people are sensitive, and that's where the problem really is. No, I'm not saying people should "suck it up", I'm saying it shouldn't be dropped so casually. It used to be where you would face a team of 5 and get all 5 spamming "REKT" in chat, often against a complete stranger who was completely outgeared. This is another way the problem shows, as a way for someone to almost stroke their own ego, whether it be because they're having a bad day, or revenge (even though it's just a game), or just because they felt like it. These two combined could usually take a simple 2-4 letters in chat into a full blown flame war. It acts as a spark to the more "volatile people". I was against saying anything like that when it was allowed because of this (unless i was having a really bad day and couldn't think straight), I didn't want to start a flame war with people unless I absolutely had to.
One thing said in the past that I have to agree with though is the logic is kind of similar to saying "suck it" because you beat someone in a game about blocks. While it may just be smack talking, i seems WAY overblown, especially when almost everyone says it.
I just want to end this off by saying I'm not trying to start a flame. I'm just stating my opinions in their most basic form.