2013 was S3. Meta picks back then were picks like Nami, Zyra, Sona, Annie and Thresh. Why was Leona never played since most of the supports played were relatively squishy and immobile? Because players would abuse her obvious weakness I mentioned. She gets pushed or hard poked/zoned at level one and then cannot engage, becoming useless.
Finally, rating does matter. If you're Master + you're relatively good, if not then you are trash. However this doesn't mean that Silver is the same as Gold or Platinum. The fact that every rating bans different picks, shows that people of different skill level fear different champions and that's for a reason. For example, people in bronze ban picks like Amumu, Malphite and Blitz. Are these picks strong? Not that much. They just find it difficult to dodge skillshots or spread against aoe skills, which sounds funny at higher ratings. People in plat ban Zed, Riven and Rengar. Are these picks overpowered? Absolutely not. They just suck at peeling, map awareness and predicting enemy movement.