Duo queue should 100% be removed from the game, for many reason in my opinion but the most important reason is due to people ending up in games that they have no business being in. It's one thing to have good synergy with a duo or more commonly be carried as a duo but it's an entirely different thing to queue up solo and be expected to be able to preform in that elo at the same level as you can with your duo.
There are many people that can get to say gold elo with a duo but are NOT able to do it solo and it shows, oh boy does it show. It's unfair to have these kinds of people in your solo queue game, if people want to play with friends they can play flex, and don't give me that, "it's not as competitive as solo/duo" bullshit because OF COURSE it's not. If you really wanted to play in a competitive environment then you should be ok with going at it alone because that's what TRUE competitive play in league is.
This whole issue is compounded by champions like yummi, a high bronze / low silver level player can get carried all the way up to plat by a good enough adc with a champion like that fairly easily, imagine if that person decided to queue up solo after that.... Horrifying. Also I feel like all of this contributes to people flaming each other, if someone is in my game that obviously does not belong there, NOT just having a bad game but actually does not belong in it that is frustrating as all hell.