When I'm first pick and someone asks for my role

I think you misunderstand what I mean if you think I would assume that I'm going to win any game I play against a high mechanics champ, and what I mean by "they aren't worth playing in lower elo" (for serious climbing that is, as a fun champ to play if you're happy at your rank they're great). When I say I'm glad to see a high mechanics champ on the enemy team, and worried about one on my team it is bc it's a coin flip. They'll either be smurfing and crush the game, completely bomb and waste a pick for out team, or do somewhere in between where they manage to succeed even though they misplay the champ a whole lot. That last piece is why I don't play Lee even though he's fun. My mechanics are shit, and even if they were okay, Lee takes way more than okay to get the full strength of his kit.

The issue isn't that you can't win w/ a high mechanics champ (and even win in a flashy way), but that if you don't have great mechanics you can't use the kit to the optimal level (which is what balance should be designed around, so unless the champ is just blatantly OP you're putting yourself at a disadvantage). The reason I mention Elo though isn't bc there's some magical pokemon badge that makes the champ listen to you when you get a certain rank, but rather that certain champs lend themselves to mechanically skilled play, and if played right WILL end up at a certain level. Game knowledge and mechanics are both important, but in general not important at the same time until plat from what I've seen. For instance, I have crap mechanics and hit gold almost solely based on game knowledge. I regularly miss skill shots, fail flashes, zhonyas/ult/whatever at completely the wrong time or when just standing around and I meant to hit enter and type. However, I gauge when to initiate vs not fight well, I make decent baron/dragon calls, and I rotate kind of okay. I climbed bronze to gold this season on this account, then did it on a second to see if I could do it w/out duo que (first time I duo'd w/ a couple people who were mechanically good and would win lane so calls were easy to follow through w/, ie we could control drag bc we had a lane winning), and when I hit around silver II mmr I started getting matched w/ people who would out play me in lane. I lose a whole lot of lanes, but usually my team ends up ahead from me taking objectives/rotating to help other lanes/etc. Oddly since hitting gold my play has become a bit worse just bc I tilt easier not worrying about missing out on season rewards if I lose a game bc I'm not paying attention well enough, so I've been doing a bunch of stuff that I'm like "wait, that was a dumb idea, I shouldn't be doing shit like that." I play w/ a lot of people who have the same experience, but in reverse; they are mechanically really good, but don't know what to do w/ the lead other than stomp their lane opponent.

The thing is that neither myself nor the people on my friends list are particularly "great" at either mechanical or knowledge based play. We're decent at it, maybe some of them are good, but none of us are exceptional at them. If you had perfect riven/zed/yas/lee mechanics you could probably play w/out a mini map and still get plat at least bc people who use their mechanics perfectly are SO dominant in lane and have SO many options in team fights that it's stupid. There are legit gold/plat/diamond players who are amazingly disproportionate in their skill between mechanics and game knowledge/strategy, and they get there based almost solely on the strength of one category. The thing is, that high mechanics champs are the epitome of this condition. Riot once said that Zed is a nightmare to balance, because if they make him good for 95% of their player base then the champ becomes a must ban champ in high elo and competitive because the players who are exceptionally above the average skill w/ that champ will have so much of an advantage. That means that if Zed isn't pick/ban in competitive he is balanced in such a way that Riot would say most people probably shouldn't try to climb w/ him and should instead play him bc he's fun. Again, it's not that he can't be good, but that it's not his full potential because of how difficult he is to play, and as a result people who are good at him would be better on a more moderately difficult mechanics champ, and people who are great w/ him (ie use the full kit instead of putting themselves at a handicap) are in high elo. Now maybe that's not true and Zed doesn't fall in that category any more. Maybe they've changed him to be less mechanically intense and a lower skill cap champ, but I can't think of any changes that would likely make that true. Personally if you have fun w/ him I think you should play him. I'm trying to get better at Nunu after switching to jungle recently, and it's entirely bc I like him and not bc he's the strongest champ I could pick. W/ current cinderhulk Nunu isn't super strong, but he's super fun. I know that though and I don't mind being at a slight handicap in order to have fun, I'd rather be a rank lower in gold than pass a set of promos and still be at gold level w/out playing something I love.