Do promos use different matchmaking or something?

Two feeders two games in a row, one of them being my ADC who sincerely thinks they can tower-dive the Leona (you know, the champion with one root and two stuns) and another ADC who tried but still, in the end, was caught plenty of times pushed past the river for no real reason at all, not even taking tower and ending up ganked numerous times by the entire enemy team. He never learned to ward, either.

Next game, a Karthus who was AFK for around three minutes, giving Brand freeroam Bot and Top in that order, topped off with a Yorick who kept calling everyone trash, even as he was going 0/5.

Does it, legitimately, just try to force the first promo to the next League to be a loss? It really feels like it, and it is legitimately the most frustrating and unfun bullshit I've had to deal with, yet, in League.