Who said that TFT is a tactic game ? Oh, they gave a wrong name.
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You can go from 1st place to last place in consecutive games just because you didn't roll RNG well. you can lose simply because you can't get silvers to show up, or because others got golds. If your enemy can get the item and champ combination right there is no counter. All of this is pure luck.
Yes but the "pure luck" sometime favor you sometimes not, so playing more games the RNG is balanced.
Only your few decisions decide your rank position, not RNG/Luck/Bad Luck.
RNG is just a funny thing. Of course comparing to LoL (100% tactics, inteligence, decisions), TFT has maybe 10% of these.
The only thing that don't work with this game TFT is ELO ranking system. In higher divisions you lose much more LP for a lose and gain fewer LP for a win. And this doesn't work with RNG game.