I don't get the Dynamic Queue elo boost argument.

There's this argument about people being in the elo that they don't belong in because high elo friends boosting their low elo friends. When I hear this the first thing that pops into my mind is "If I was a high elo player, why would I go through all the work and stress to get my friend to a high elo when I could elevate myself and rise higher?" Let's be real here, if you got to Diamond you're about 10% of the playerbase. You remember all the struggle and hard work you had to do to get there, why would you go through all of that again when it doesn't benefit you? The way how I see it the low is elo player causes his high elo friend to have a disadvantage in solo-Q. The higher he goes up with his friends the more of a dead weight he is to his team, it's essentially a 4v5 because the low elo player(Who doesn't have the game knowledge and mechanics required for that elo) will pretty much feed and make more mistakes pretty much all the time, this player's mistakes will cost you many games and make it harder for the high elo friends to carry. Let's say the low elo makes it with the big boys and gals and at diamond, you pretty much won't be able to get any higher dragging this friend that does belong on your team so you might kick him out. Now the the low elo player has to survive and his own and will surely drop his elo back down, it can happen rapidly or slowly but he's pretty much guaranteed to drop. This is what I think about this argument, but hey what do I know? I'm just a silver scrub.