Has any credible source said "to climb, play random champs"
I ask because I've never heard it. It doesn't seem to work. The opposite is suggested and shows results over many samples.
And I also ask because if playing random champs every game doesn't help you climb, and ranked is about climbing, why are people allowed to play random champs left and right? We don't let people feed because it's not a winning strategy - so why do we let them pursue other non-winning strategies?
You really should only be able to play Mastery 4 champs or higher. And the failure to enforce some mechanism to prevent people from just randomly selecting champs is infuriating.