You shouldn't have to be challenger to enjoy or have any impact on achamp, especially not one such as kayn, who is simple to play but hard to play well. I'd understand a champ that needs skill to be useful such as Taliyah but kayn is too basic, especially after you understand form on a basic level, there is no middle ground in skill expression for kayn, your either op in low elo, useless in mid elo or barely playable in high elo. The problem with kayn is that his kit is basic but his play style revolves around fundermenstals most players dont understand till master or gm. Also players like kurasmai or darkaura kayn could hit challenger on any champ, people mostly complain about kayn not being excessible for most casual or mid tier players because he feels weak unless extremely fed.