The RNG is really that bad. One game isn't proof, but seeing a horrible disparity game after game is. Some players will have a 3-star carry by round 2, while other will struggle to upgrade all of their champ to even 2-star even if no one else is using them. In fact the disparity seems to be getting worse. Some level of skill is still required, but it doesn't necessarily win you the game; Players who seemingly have no idea what they're doing will stumble into quick upgrades and wipe the floor with you despite having no team synergy and no idea what items to put on what champion.
The item rng is another issue. Some people will get two carry items in the first round, some people will get a ton of gold, some people will get nothing at all. And the entire carousel idea is awful; lets face it, it's just a fight over the spatula or one of the carry item pieces, and the fact that if you're winning you'll never get another spatula off the carousel again and they almost never drop means players that are actually going to stay in the game will almost never get to build a spatula item to fix their team synergy. They MAY be able to snag one later from the carousel that has complete items, but there's no guarantee the one you need will be there. Same with the dragon drop: one person could get an absolutely useless synergy item and another person could get a deathblade or hurricane, something that massively increases their dps.
Everything is random chance. The game isn't how well you can strategize and team-build, it's how well can you struggle through these random die rolls. You might get a stick and the person next to you might get an automatic rifle, but you'll just have to do the best you can with that stick. You may know exactly what minor adjustments you have to make to your team to counter what other people are playing, but that doesn't mean the game is going to let you do it. Go ahead, burn through 100 gold rerolling, you aren't going to find that Lux, or whatever champion class or origin it is that you need. Oh look, the game gave you two of each light champion, and nothing else, in the first round. Might as well go light, right? Too bad you'll never see another one again.