Flex 5V5 is just as bad as normals

Why is it that Flex has such a huge gap between players rank? I know it has to do with MMR but come on. When you have level 30's who are going against Plat V and above that is just completely broken. It just creates an excuse for people to fuck around because its "flex" and not take it seriously when others are trying to win. Flex is pretty much normals with a visible rank to to it, and it feels like Riot just put it back to pander to those who were complaining about ranked being all one.