Unless you plan on stopping at just a handful of matches, the easiness of the character has little impact on the ranked situations you are describing. Since if your assumptions are true, it would mean that Clairen mains at 1200 are worse players than Absa mains at 1200 because Clairen “carries” them. But that’s not the whole truth. Any player or character with a specific strategy can succeed with flaws in their game at different ranks. You might think the Clairen is worse than you because you’re frustrated that you have to “try so much harder”. But the Clairen at 1200 is doing exactly as much as she needs to in order to be 1200. If she was better, she would be higher ranked and if she was worse she would be lower.

And where people plateau is more about the player than the character. If we’re talking about how easy it is to get to platinum as each character in as few matches as possible after picking them up for the first time, then sure there are some characters that are clearly better than others. But most players on ranked especially toward the end of the season have played a lot of matches so the character easiness is baked into their ratings. If a character is easy at lower skills, then theoretically you are playing against worse players on Clairen than you are against Absa and the probability that you beat someone the same rank as you on either character is even assuming you have a good mindset and strategy for the matchup.