Why Do LCS Teams Only Pick OP Champs...

Because RIOT balances game around bronze league.

You can have 90% champions picked in League as well, but the cost would be the total destruction of low elo soloQ balance.

Dota balances for competitive play first and foremost. If that results in something being busted at low elo, well, bummer. Better stop being bad and climb out of low elo then.

Consider picks like Amumu or Volibear, which are not viable at the competitive level because they have very exploitable weaknesses (weak early game/extremely kitable respectively), but are still very strong at low elo. Then imagine Riot buffed those champions to the point where they were viable competitively. Now those champions would be absolutely fucking broken at low elo with 60%+ win rates.

That's what Dota does. And when people say "but Omniknight is so OP it's unfair" the response is just "get gud".

I'm not saying that's a better or worse approach, but you have to understand Valve and Riot have fundamentally different balance philosophies. Valve balances for competitive, at the expense of some champions being busted for most players, while Riot balances for the majority at the expense of lower champion diversity in competitive play. Just the way it is.

Also the pick/ban structure is different in Dota, and there are champions that are legitimate hard counters to others (which doesn't really exist in league, and can't because not all champions are free). It's just a different game, apples to oranges.

Because counterpicks in league don't give you enough % points over just picking a better champion and I suspect that champions in league, particularly the OP champs are OP because they are versitile enough to fit in many different comps.

Keep in mind I think + bot lane is an OP comp made of okay champions so they do still do it from time to time.

thats what they do ROFL

Currently the best teams almost never lose a game when they can get advantage in the early game. Therefore if you pick op champions and win lane you will win game most likely.

Because they have been set up by Korea to do this, so when they play at international competitions, they can wreck them using OP comps. See MF support for obvious evidence of this. NA and EU have been made to just follow what Korea does and not innovate on their own. Feels bad.