Why am I up against gold/plat players in normals

So as a player mostly play normal games and for the most part was matched around similarly skilled players and most games never felt that the games were unfair in terms of player skill though that has changed at least in my games starting around late season 5 or early/mid season 6 games started to feel like I was just outmatched. I was just getting stomped game after game to the point where it became so frustrating because I couldn't compete and was/is still losing a lot of games. It was like my opponents were getting better at a way faster pace than I was to the point where the skill gap was so wide it just wasn't fun anymore. I don't think I had a major drop off in skill while i'm nowhere near being a good player I don't think I have gotten worse(though that might be the case)' I started looking at my opponents now for the most part I assumed most were unranked like myself but to my surprise I found that most the people I play against range anywhere from high bronze to low plat in terms of ranked. While I know normal's have a hidden ranking that is separate from ranked MMR and that you can have a high ranked MMR but a low normal MMR, but that is a huge skill difference and I while I can mostly hold my against the bronze and low tier silver players the games where and the odd case when I play up to a higher skilled opponent. the games where I get higher ranked players are getting more frequent and I know I should be trying to learn from them but they aren't fun just frustrating because I'm nowhere near that level and instead of being a steady progression into better players instead its just a huge spike in difficulty and I would like to know why.