5000 Kills for the monthly is a bit ridiculous. Especially, that I made it to SR118 with just over 6700 kills.
It's really not. If you can manage a minimum of 167 kills a day, you'll get it. Just playing for a couple hours should get you more than the minimum amount you need to stay on track. It's really not too hard. Besides, I'm happy that this is the first challenge that presents any sort of challenge, even if it is pretty minimal. After having win 30 games in a month, this is a welcome change.
That being said, 130 is crazy easy to hit in this game, and challenges are meaningless once you hit it.