Random thought: Why does LP gain/loss differ every game?

This question was provoked by myself ending up with 97-99 lp quite frequently. i was wondering why this always happens, its one of the most annoying things in league to me. i always sucks to put in so much work for a win that FEELS less valuable than all the others. Is it technically more or less valuable? thats up for debate, and i think would ultimately be opinion based. But this isnt the main point i want to address.

what if 20 lp was granted per win and 10 lp subtracted per loss(basically a fixed number) from my basic understanding of the lp system its based of mmr of your own, your teams, and your enemies team: a number which has nothing to do with anything about THAT game. idk something about it bothers me that i cant actually see why i get certain numbers that are awarded to me. A win is a win and should be equal :^) this is obviously trivial to other concerns about the ranked system in general but i find it interesting to think about the What If's. i like consistency and planning ahead(reasons why i like this game) it would be nice to have confidence going into a ranked game saying ok; if i win i have to win 2 more to get to promos, etc. would this be better? maybe? not sure how you feel about this, its not likely to change but again i enjoy the theorycrafting and such