Losing a promo because of dodging is the stupidest thing ever

i was in a 5 match winning streak, and already won 1 promo game, i dc-ed in my 2nd promo (in champ select, before choosing a champ even) and that counted as a loss, now why the hell is that ? my third promo game has ended with a loss because of 2 trolls in my team. Now i know that some people dodge on purpose (and not dc like i did) but seriously, it counts as a loss ? why ? at least give us 1 chance to dodge while in PROMO GAMES. god knows if we meet a troll or just... dc ?