My arms are finally 17"+, so I figured "why not?"  Excuse my ugly mug and piss-poor posing.

Just a couple of years--I'm not very serious about watching my diet or getting enough sleep though (my job makes it difficult to do either). 

I don't really plan to cut.  I'd like to focus on strength gains, to be honest--I don't particularly care about having a six-pack.

You're the noob.
But since i'm trying to save this forum from being all sarcasm
and no explanation, i'll tell you why.
You're a noob bcos u think squats = leg only.
Maybe becos u've never squatted heavy before. When u go heavy,
u will utilize ur arms to push the weights up too. Afterall, it's a compound exercise.
And squat is one of those exercises that improves overall mass.
'cos face it, if you're a stick figure guy, u'll never be able to get 18" big gunz...
big gunz comes with big everything.