Garen doesn't really function as a DPS. He dishes out about the same amount of damage when built as a tank and that way, he can.... tank. He has 1 small MS buff, no slow/snare/stun, and Judgement shouldn't even be considered helpful to a melee DPS build because it prevents you from autoattacking for its duration, severely gimping your damage output. Now when your a tank, Judgement is great because it is increasing your damage for that whole duration, while also removing/shortening slows. Sure you can build infinity edge and youmuu's on him and kill people, especially if you're not summoner level 30 yet and people are still learning how to play, but you can also get kills as a tank and be 20 times harder to kill.