I'm extremely tired of this argument as well. Just because RNG is part of the game mode doesn't mean everything has to be completely RNG.
I am OK with the current way of obtaining champions (e.g., rerolling), I am OK with getting different items than the ones I want, and I am OK with how most champion passives work. Two of these things make the gamemode what it is (it would be wildly different if everyone could choose whatever champion/items they wanted from an infinite pool of both).
The important thing is that with differing items and champ rerolling is that you can work with the RNG that you get. No item components are useless, you can pick up item components at carousels to better work with what you have, and you can rotate what build you're playing mid-game if you realize you're not able to get what you want.
I am NOT OK with facing the same person multiple times in a row due to RNG, I am NOT OK with being at a power disadvantage due to less items, and I am NOT OK with the carousel being luck based. All of these things are not required for TFT to maintain the core pieces of TFT. The game would not radically change if a pseudo-random system made sure you couldn't fight people again and again, everyone was given the same number of items (but different components, OFC), and the carousel was a stationary line of champions (or something).
You can't play around getting unlucky at carousel (other than settling for something you didn't want) and you can't play around fighting someone multiple times in a row (can't rotate team comps effectively at certain stages of the game, plus you're risking tanking your econ for nothing if you don't fight them again). You can play around not having as many items as you want, but being at a blatant power disadvantage just because of RNG still feels like shit.
Additionally, just because this gamemode is based around RNG doesn't mean that all RNG is good for it. Imagine a mechanic where you had a 5% chance of being executed, regardless of how much health you at, on every new stage (e.g. on 2-1 you could be executed, 3-1, 4-1, etc.). This mechanic would have 0 impact on climbing because everyone experience the same RNG and it's RNG (which is integral to the gamemode), but does that mean it should be in the game?
No.