People seem to be throwing the 5% they read around willy-nilly without realizing the emphasis of it. This isn't, "One in twenty of your solo queue games will be against a premade 5," but rather it's, "If a premade 5 plays twenty games, odds are one of those games will be against a non-premade 5," that being them matched against either a "4+1" a "3+2" or even a "3+1+1" on slower days, not the "5 vs 1+1+1+1+1" that everyone's shouting as if it will be a common occurrence.
Let's also remember that it's not going to be a consistent percent across all ranks. The majority of the NA playerbase is in Bronze & Silver, so premades in that tier are more likely to play against premade 5 groups since there's a larger pool of players to match together/against. The majority of the players, on NA at least, are not likely to run against uneven teams because of the large pool of players at lower tiers. Once you'd look at the higher ranks you'd see that they are the ones more likely to run into the "5 premade vs 4+1" games. Combine this with the fact that they're still keeping the condition that the people you queue with have to be a similar rank to you and you realize that you're far more likely to run into either "3+1+1" or "2+1+1+1", the latter already a possibility on live. And even with that last part, they stated that the penalty of queuing with a teammate will no longer apply, so getting a "2+1+1+1" next season won't be as bad as it was for previous seasons.
Is a team of 5 people more likely to win against a 4+1 assuming they're the same skill, yes. Was this a problem we had to deal with in previous seasons, no. But the way people are talking about it makes it seem like people expect there to be a premade in every game, when in reality we're only supposed to expect a small bump in non-solos in ranked. If they made the queue with friends bonus similar to the bonus party IP, I figure that people will consider that a negligible bonus to playing with friends since nobody talks about that and it's never a thought when I see my friends on. In fact, with the keys coming, you get an increased chance to benefit from the system if you win, meaning that queuing with a friend that you know isn't going to help you win much may end up costing you not only the win, but a chunk of the benefits that go with it.
And to chime in with my personal experience regarding the toxicity everyone's expecting from premades, I don't know how all of you choose your friends, but I've removed people from my friends list that I knew in real life because they were toxic. I know toxic people are less likely to stay focused, so I wouldn't want to go into ranked with them knowing that they may turn defeatist after a single misplay. If you're in a ranked game with one of your friends and they're being toxic, you don't have to confront them or stop talking to them in real life, just don't enter ranked games with them. Play an ARAM, Team Builder, or Draft match if your friend can't manage themselves. Since I tend to actively avoid mob mentality and am willing to cut people out of my life on a moment's notice that may be a little easier for me to do than others, but there's a simple golden rule that everyone knows and they choose whether they follow. So I hold strangers and friends to very similar standards, if they don't care about others I won't care about them.
TLDR (despite you benefiting from reading it all) - I expect next season's ranked to be very similar to this season's. People are taking the small percent chance of something bad happening and acting like it will be a common occurrence and a far worse one than the reality of the situation would make it. In fact, because the ability for us to choose two roles to queue for will be coming, I won't have to worry about the "X or feed" popping up as much, or even having my preferred roles taken by the pick priority which was entirely out of my control.
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