The reason dynamic queue still exists
This will be hard for you guys to hear, and I know you will downvote me because you don't want to hear this, but I need to say it.
Riot makes more money with Dynamic Queue. People are much more likely to give RP to a friend with dynamic queue, invite thier friends to play, and generally increase the popularity of LoL when friends are involved. It's that simple.
"But ranked integrity!!" you might say... Anything below Diamond has always been a joke to Riot. They will never balance the game around anything below Diamond, and they will never, ever take it seriously. Riot could not care less about your rank or if you feel "cheated" in ranked. They know you will keep playing the game. The only person who cares about your rank is yourself.
Riot is essentially just your drug dealer. If the "quality isn't up to standards", they don't care. They know you will buy (play LoL) anyway. They want to make money.
Tl;dr: Ranked integrity is a joke to Riot, they just want money. (It's almost like they are an actual business!)
PS: I do not endorse Dynamic Queue
