Broken Ranked System and Hidden MMR

Why is it that there is supposedly a hidden MMR system in place but you still cannot go into a premade with friends if they are more than one rank apart. Not only that but why is it that once you hit diamond the difficulty level increases like it did before? The point I am making is that the ranked system is trying to do too much all at once and also allowing people to just sit and camp and do nothing all game (aka Valks) and still get rewarded for poor group play. If there is a hidden MMR system it should still be in place no matter what rank you are if that's the route you are planning to take with ranked. Don't feed us this bs that once you hit diamond the skill level increases suddenly as if the hidden MMR means nothing. I am not a great player and yes I am just about to hit masters for the first time though pairing me against top 100 preds every game and expecting me to have any chance against them is just poor design. Not only that its incredibly unfun to just throw me in a game where I just get rolled by players whom have an entirely different skill gap than me. Judge me all you want but the rework of ranked has been a total disaster every time it has been changed.