Alot of players think that a team having more tanks being high win rate means tanks are OP.

I disagree.

The reason is simple: it takes less gold for tanks to become useful than carries.

The map has only so much gold. Every jungle creep or mid game wave that you take away from your carries as a top or jungle is denied to your ADC and mid. Normally that's not a problem in low elo but in extremely high elo (d1+), it is a punishable mistake.

A team of 4 carries + 1 "support" Lux/Brand with a Doran's Ring is going to have 5 players with mediocre amounts of gold that are all useless with that much gold.

A team of 1-2 carries, 3-2 tanks and a support will have 2-3 underfarmed champs, but they don't need that much farm and are useful without the farm, and 2 super farmed carries that are all 1 shotting everything.

This is why in pro games you have teams that ignore their top laner or have the top laner abandon lane to avoid feeding an enemy carry and just go double jungle - they can always just build full tank with their limited gold while still being useful.

Meanwhile in bronze and silver, the full team of 4 AD glass cannons + "support" Brand with a Doran's has absolutely no idea why nobody on their team has gold and why the enemy team takes 0 damage from them, thus "tanks OP".