Bad players farm themselves to gold... Blame to points system for being too forgiving. What you actually want it better matchmaking and a different point system. If that actually happened though a majority of the playerbase would be stuck at silver+gold with 0 hopes of escaping.

Some gold players want to be in diamond matches a lot of the time. Those same gold players are liabilities in diamond matches. If someone is stuck at gold for days, or weeks, there is more of a reason to be stuck at gold than a bad streak of bronze healers.