Questions for Riot about matchmaking and balancing teams. Particularly in Flex, but also in Solo/duo

Why do I have to vs DIamonds when I'm Gold 1 in solo/duo?

I know why. But WHY. Why can you not just let me vs Gold 1's when the rank you're giving me is gold 1? I had to struggle to get a mere plat 4 this last season only because I had to vs high plat and low diamond to climb through gold 1 promo. Which I failed to promote 5 separate times. Also being gold when your team mates are all plat 1 and diamond 4 leads to some pretty sub par games. My team mates automatically assume I'm trash and abandon me all game. When most of those games I happen to have the highest farm, most kills, and least deaths by the end. If it was a normal game where people just played normally around me many of those games I would have won.

But the crux of all of this is Flex. Why do I play Iron in flex? Then why am I vsing high gold- high plats while in bronze and iron in flex? No one has time to try and climb in flex when everyone is 2-3 full divisions below their actual ranks. I'm not condoning smurfing, but I have played on one of my other accounts a few years ago that I placed into bronze on purpose because I was bored and wanted to prove to my bronze friends that if you're better than the rank you can easily climb out. I won 100% of my games in bronze, and probably 90% of my games in silver before I got that account to gold. And it still took 50+ games. For me to climb in Flex to gold it would take 150-200 games minimum. How is that okay?