No idea why anyone would be against limiting ranked queues to solo or 5 stacks to keep it easy to balance. Whats wrong with just playing normal games with your friends if you cant find 5 to play with?
Also disagree with murray, comms at any level makes a big difference to call for good plays/ganks and communicate strategy effectively. Even if only 1 other person on your team communicates well it can make a massive difference.
Player skill is a small part of this game, its a team game at the end of the day and no amount of skill (seriously, there are like 4 buttons get over yourself) is going to make up for an afk or some feeders on the team under normal circumstances. Even taking something like a lycan/prophet to solo push is no good if the enemy fives up and smashes down a lane feeding on your team over and over.
I kind of agree with wanting to play vs only solo quers when I'm soloing (sometimes it gets really annoying if you have a terrible stack on your team and the enemy stack is decent) but it isn't the end of the world if you play vs stacks, I've won just as much as I've lost vs stacks tbh.
As for communication, I actually have to say that the better people get, the less communication you need, I que all the time on russian servers and get full games where I can't read one word for 40 minutes but as long as you know how to read the flow of the game so to speak you don't really need to communicate because you already know what you need to do, where you need to be, what your current priority is etc. (obviously at lower levels communication would be more vital, also this is just ranked pubs I'm talking about).
The thing is though, my point above is only really valid in the 4-5.5k regions roughly AFAIK, when you're below that or you want to break above 5.5k and hit 6k+ a lot of the time you will need to communicate a lot (I learnt this the hard way when trying to break 5.5k) players like fata got to 6k+ the fastest because they went Ranked CM mode, picked himself a snowballer mid and would just call every movement on the map (when to rosh, when to smoke, when to push) for their team and pretty much spoonfed them the win, not to take anything away from his skill as a player but it can be so hard to win some days.
Also I noticed a comment below saying something about 1 year can improve you a lot. I think even in 6 months any 3k player could get 5.2-5.5k, it's just a matter of playing to improve rather than playing to win, you can play every day for years and not improve at all (I've seen it a lot of times) but if you're actually playing with the aim to get better and doing it correctly you can improve very fast, but it is pretty hard to improve on your own, Dota has always been the type of game where someone better than yourself could tell you something you're doing wrong or something you aren't doing at all and you would be like "I can't believe I didn't think of that, it's so simple" and it can improve your gameplay 100x over, but you can also be told things that can't really be explained outright (can't even think of example right now) and you have to look out for these things and experience them yourself then somewhere down the line you'll suddenly understand wtf it was that you were told so long ago, I swear this game is like a more modern or "futuristic" chess, the more you play the more you realize you actually need to learn and just how complex the game is.
I didn't mean for this post to end up this long, it's pretty late and I'm tired, sorry if it was boring!