Let's start by assuming you're correct, even though you have a sample size of 2.
If matchmaking really was fucked up, "gold" and "diamond" would be meaningless, since you can get matched up against anyone anyway. Basically, if the game isn't going to create even situations in terms of MMR, you have basically a 50% chance that your team of golds and silvers is actually higher skill than the enemy plats and diamonds. Literally, in your point to say "rank isn't a display of skill," you say "gold players vs. plat players is unfair and uneven matchmaking." So...rank IS a display of skill.
What are some reasons a game might have been golds vs. plats and diamonds?
- the plats and diamonds have tanked their mmr from bought accounts and are on a steep decline to gold
- at least one of your golds is a booster or bought account
- you're the best players in gold facing off against the worst players in high plat, for a game that has an average elo of around plat 3 or plat 2.
- You are queueing at 3 am and this is the most fair game the system could possibly offer you
- op.gg is wrong and the ranks are actually closer together than you think
Basically, quit yo bitchin