That's unfortunately all too common a mistake on Boards. I've seen many a discussion get completely sidetracked because someone could not differentiate between balance or design: when someone says a champion is "good" or "trash", they're typically referring to their power level and state in the meta, and when a champion hits that special spot where they're neither too strong nor too weak, nor exceptionally prominent, it's difficult for most players to care about any requests to change them, even if they have design problems, because they think their play/win stats are the only things that matter. On the topic of tanks, it's often difficult to move the subject of conversation beyond their skewed balance, because pointing out ~40% win rates is easier than giving a detailed analysis of where the updated kits fell short.
What upsets me especially about this is that these communication issues end up having serious long-term consequences, and make a ton of noise about what is ultimately just a very short-term issue: in just about a month, maybe two, Riot's going to pull whichever levers they have to in order to bring tanks in line, whether it's by buffing those affected by the Sunfire Cape nerfs or nerfing outliers like Sejuani. These champions' play/win stats will eventually move towards normal levels once players gets used to them, but their design will stay the same, possibly for years to come.
What's worse is that this is supposed to be a keynote update for tanks as a class, or at least vanguards (which I think should be split into two more subclasses, but that's a topic for another discussion), so if the direction picked here is wrong (and I think it is), it could mess up tank design for many more seasons before Riot realizes their mistake and painstakingly undoes the work they began here. I don't particularly care about whether Sejuani is OP or UP at the moment, that can easily change very quickly, but I can predict that, once she falls in line, her design and power allocation issues are going to make her difficult to balance properly and not all that fun to play, and that's going to gall her until she receives a full VGU. The same can be said for many other tanks, whose nukes are going to either feel weak or extraneous as balance shifts, and that's what I think should be the focus of the update's feedback, not just balance complaints that Riot can easily verify on their own.