[2019] Why as a level 50 i have to play against people with level +100-150 and sometimes even 200

Hey guys! The Quick Match/Casual playlist does have its own separate MMR that is invisible. If you are playing against someone who has a high rank, it would mean they have a similar level of Quick Match MMR. This could be due to them not playing very seriously or not spending much time in Quick Match as opposed to Ranked.