Ranked LP Gain / Loss

So over the past few days I have been talking to a rioter on support asking how totally identical accounts (me and a friend) have different LP. I was saying how only losses and wins matter, and depending on how big of MMR difference between the two teams. I even looked up on the support page and it says that KDA does not matter. https://support.riotgames.com/hc/en-us/articles/204010760-Ranked-Play-FAQ. Under What determines how many league points I get from winning a match? It Says that "Being a part of a duo, kill/death ratios, and other statistics does not affect your LP gain."

So when I was messaging the rioter he said that KDA affected LP gains and losses as well as winning or losing the match. Unless I am reading that part of the support page wrong, I feel like that should be changed. Because although I have been playing the game for the past few years, I was always told that KDA doesn't matter because of this support page. It could also give new players false information too.