Why does league only punish AFK players...

...when they AFK at the END of a match? I just had our ADC come "reconnect" at 13 minutes. We already lost two bot turrets and their Sivir didn't miss a single CS; and they got 2 dragons.

And she doesn't show as red end of match, i.e. she is not going to get in trouble. Why the hell not? We lost 100% because of her...(well, at least 75%)