WHOA hold on. How can you possibly say that a try-hard ruins the game for ANYONE? No one is forcing you to pick riven/kat/meta champion. You say the game isn't challenging but complain about people picking strong champions - pick an off-meta champion and take the disadvantage and there's your challenge. You say the game isn't challenging but complain that as silver you're against Platinum players - actually play against them instead of giving up and feeding or going afk, there's your challenge.
A try hard does not hurt anyone else's experience. They play to win. Short of them dodging your bad picks (in which case they have a time penalty and you can requeue at no cost) they only affect your play positively. They try to win so they aren't feeding your opponent making it impossible for you to play because someone on the other team can win a 1v5 fight.
The people with the "I want to mess around with a bad champion who is ad scaling except one skill has a 0.2 ap ratio so I'll go full ap and see if I can get a burst kill on their tank"-attitude are the ones who ruin the game. The ones who say "it's normals who cares" are the ones who ruin the game. From the sounds of your post, it's players LIKE YOU who ruin the game for most players.
Want to play something silly AND make terrible decisions in game? PLAY A CUSTOM GAME WITH YOUR FRIENDS OR EASY BOTS - don't come to normals and force people you've never met and who may want to play legitimately to cater to your silly needs when you can do exactly what you want in a custom game with people you know!
I have no problem with you doing something off meta but doing it right. Go viktor mid? Sure, he's terrible in the role right now as far as I'm concerned but if you play cautiously and build ap and magic pen I'm not going to care much. Go urgot top? Fine, just build him right and don't tower dive at level 2 please. The problem is you want to go ad Fiddlesticks or ap ashe or something... That garbage is for custom Games or bots. Don't make someone else not only lose but have to play for 35 min because you won't surrender yet you fed your Lane opponent 8 kills before bot Lane hit 6 and now they're roaming and 1 hitting everyone on the map. Some of us (MOST of us) that play normal Games (ESPECIALLY normal Draft) do so to practice for ranked because they either have insufficient runes or champion pool or want to get better in a role, etc... Not because we want to just accomplish irrelevant side goals like dealing over 2000 damage using an adc's ap scaling ultimate. We play normals for fun but WE ACTUALLY FIND THE GAME FUN, or at least a close game is fun.
If you're so tired of this game that you no longer have fun playing the actual game (again, feel free to play any champion you want just build them properly for the role you're playing and play passively don't go tower dive at level 2), then you should seriously consider why you're still playing League of Legends and should probably move on to something else...