Eh, only to a point. As a few people here have already commented, at the end of a game "ez" is just flat out griefing and I will report it every time. Especially when the whole game was a back and forth and everyone was putting in extreme amounts of effort; that's just plain disrespectful to an honorable opponent.
I will also report someone who has been having a massively amazing game, is going 20/0 and just one shots everyone on the opposing team, when they call out "ez."
However, in the heat of the moment, when someone who is not fed fights out a particularly difficult battle and responds with "ez," I will laugh every time. Totally earned and totally okay in my book.
And most of the time, I will let the losing team call out "ez" at the end of the game. If that's the ONLY thing they've said that can be recognized as griefing or negative, I'm not going to worry about it because they're probably joking. But if they call out "ez" at the end and have been toxic/negative all game long? I'll report, and I highly doubt that the "ez" is what throws them over the top.
Just my thoughts.