Yes I think it's 100% rigged. And it's so that the majority of the player base stays around the same rank. Why? Queue times. I've never been to Immortal but I've seen people comment that they smurf because queue times for Radiant/Immortal are too long.. sometimes an hour wait.
Now let's apply that to all ranks if players are more spread around ranks. With everyone cramped into Silver/Gold/Plat, your Queue time is guaranteed to be less than 2 minutes at any given time. If people are spread around ranks more, your queue time might be 10 or 15 minutes.. This will turn people off playing the game and lower the player count.
This is why I believe there is a winner and loser island. I have noticed when I'm on a 'winning streak', my team all has great comms, players knowing what they are doing, no trolls, no afks, no throwers and my aim feels insane. But then I go on these huge losing streaks.. and this is what happens... no comms, useless team mates, trolls, team killing, afks, throwers.. all of it.. And this is GAME AFTER GAME AFER GAME, until I rank down 2 or 3 ranks! It's happened to me for the past year of playing comp in this game. Everytime I reach a certain point I play game after game that is a nightmare to get through. And to top it off, my shots feel terrible. I feel like the enemy sees me before I see them. I feel like I'm being shot once, but I get hit 4 times. Shot behind walls, shot by running people. It seems like the entire other team is cheating.
I'm done with this game. I'm sure its rigged.