Your visual rank doesn’t match your true skill rank. They said matchmaking is done on true skill level. So while you may be facing a lot of bronze or silvers, the majority of those are also higher in true skill rank; meaning they too were onyx/diamond last season and are working their way up.
I think they started everyone at bronze to decrease the bottle neck effect. Those like you who are master will obviously rank up super fast after some games.
You are not really ranked against anyone. Your total team points should be relatively close to the others team. So while you may be playing with a silver as a master, the other team may be all gold and a diamond to balance it. With you being so good, you will be needed to help with the win.
The system isn’t perfect. But it’s better than Gears 3 where everything was truly random.
Quitting is an issue. They said they are working to make players play an X amount of social games before being allowed back into ranked. Hopefully this keeps quitters out. They also stated there are new players who play ranked that may not understand the quitting aspect.