Normal ELO and how it works?

Does anyone know exactly how normal elo works? In ranked I get frustrated and finish in Gold 1 every season because I get annoyed. But in normal games, regardless of which type, a majority of players I play against are high plat/low diamond. Can anyone explain this to me? Why does this happen? I'm not complaining; the higher caliber players are the reason I prefer normals to ranked. I'm just really confused about how it gets this way. Wouldn't a normal MMR nullify the entire point of ranked?