I think you are trying to define values that are not easily quantifiable. How do you mathematically quantify “player quality”? Also, the reason why “account experience levels” are not accounted for in matchmaking is that it would negatively impact matchmaking in many ways. It would DRAMATICALLY increase queue times for low-experience players when they first enter competitive play to being HOURS long, while that would put a stop to alternate accounts, it would kill this game for attracting new players and eventually cause the game to die out overall.
Competitive ALREADY does not account for Quick Play or any other game mode to develop a player’s MMR. A new player starts in the middle of the road value which is approximately at 2350 SR. Endorsements have no influence in matchmaking either. Endorsements are only an optional factor in Looking-for-Group settings set by the group leader.
Rank resets do not happen in Overwatch. The problem is that matches become EXTREMELY inconsistent for all players. They deliberately stopped doing rank resets in season 3.
I think you have a lot of impressions about Competitive that is not true. I suggest taking a look at this guide made by Kaawumba here as it really breaks down the facts and myths of Competitive Play.