It is.
IF you can prove Game Play Sabotage and get enough people to vote on it.
Correct
- Unless you’re boosting. Then that’s against ToS. But very difficult to prove.
Kinda yes, but not really…. This requires a much longer explanation of how match making in Overwatch works and I just don’t feel like writing it out.
- You can read about it here
In short, if I (a Masters DPS) jump on an alt in silver/Gold/platinum, the game tries to find other players to match me with to make the game fair and balanced.
When the game cannot find “1” person, it’ll bring in 2 people. If it can’t find 2 it brings in 3, and so on. But the game can only have a match variance of 40/60.
- IE a 40% chance that one team might lose and a 60% chance that the opposing team will win.
Those are the ABSOLUTE defined HARD PROGRAMMED limits in the game. However, a Masters DPS is going to yield too much value in low Elo, so the game rewards the player with large SR boosts in an attempt to shove them out of low rank so they can be matched appropriately.
- Please follow link above for thorough and in-depth explanation and understanding of Overwatch Competitive Match Making.
Quick Play and Competitive have completely separate MMRs
- Per Papa Jefe
Lol…. I once got rolled in masters by a doom/tracer duo.
There was NOTHING I could do to outplay these dudes.
Clearly T500 duo doing unranked to GM. Needless to say I lost that game. 
I was so desperate to try anything, I tried torb. Tracer just ignored the turret sight-lines. Doom rolled my tanks and supports. I think the enemy tanks just chilled on point all game