Maybe you got banned on one ranked account for x number of days, but don't wanna NOT play, or start a brand new account. Maybe your account got hi-jacked? Maybe you're at such a slump at your higher tier'd account, that you decide to go climb one of your other accounts out of a lower tier? Many reasons. Not a waste of time. I can recall one time I was sitting at 1-1 in my 3rd promo to Gold 3 and I decided to just give it a break, maybe I won't get a troll on my team if I wait a few hours to play this last placement match, so I went to play some ranked on my other account. I get bored of normals as I just eff around and do stuff like ADC annie with some Runaans Hurricanes, a TF and a statik shiv. Fun sometimes, but not for me. Idk, I just threw out some reasons as to why. Some people do it just to feel superior.