I'm sorry but the points being made against the OP are either extremely minimal or just aren't good counter arguments. The only thing this can do for ranked is good. Here are my arguments against the counter arguments:
@DrNova
This is a really bad idea. Honestly, think about it. If someone is (pardon the rudeness) stupid enough to bring a brand new champ into ranked without practicing to see if he's worth playing with ranked, they probably aren't good anyways. They can just as easily bring some other champ in and suck it up just as bad. I've seen plenty of the games true OP champs come in and be played like garbage.
I'm sorry but if you "think about it", a bad player playing a champ they've never played before is just going to make them even worse than they already are. I'm pretty sure I, and everyone else here would rather a bad player play with a champ that he's comfortable on rather than a champ he's never played before. This argument hold no leverage. It's the same thing as a good player playing on a new champ and playing worse. It sounds like the argument you are trying to say is that if a bad player were to play on a new champ, they would be just as bad as if they played on a champ that they always play which is false.
@Orbv
His previous point still stands, the ally could take in another champ they have never used before and just purchased from the shop and use that champion in ranked.
I don't understand what you're trying to say here. If it were up to me, I would also take the ability to play a champ that was just purchased in ranked away for a certain amount of time as well. That will probably never happen but that's besides the point, taking away the ability to play a completely reworked champ/new champ will do far more good than bad. That argument is just like saying that Riot shouldn't punish people for being toxic or afk'ing because people will be doing it anyway when the reality of it is that they may not get and catch everyone but it is doing far more good than harm and reducing the toxicity in the game.
@Orbv
You even pointed out that normals are a different ball park, so why would it matter if they took them there or not? Bad players will be bad no matter who they play, and if they wanted to try something new, be it a new champ, they would have used one they normally never used regardless. That is the only times it happens, if they obviously wanted to win they'd use their best, but their concern is more with trying new to be able to post "New SION broken gg".
The OP didn't say anything about players not being able to take new champs into norms, in fact that is where they should be taking them to get comfortable using them in a PvP environment. As far as the second point, bad players will be even more bad if they choose a new champ and they most likely would not have chosen a champ that they have never used regardless because the only reason they are choosing this new champ or any other future released champ is because the champs are hyped up and brand new and yet again beside the point. It's better to reduce the chance of them choosing a champ in ranked that they've never used before than do nothing at all.
@Orbv
Also there are players who used Sion in the PBE, myself included, who can win in ranked with him, albeit not easily because he's not really that great. It's unfair that some people lose with him and others don't but both need to be punished because the majority are bad players.
True, and I get what you're saying but the fact is that the PBE population is probably less than 1% of the population of the game and it's only fair to sacrifice some time of ranked play for the greater majority of the community and even yourselves so that you don't get a player like this on your team. That's the same thing as saying that the upper class 1% of America are more important than the other 99%.
Have one more that I'll counter argue to finish off on the next post below
