This point is a pretty common complaint. To give you an example of another thread with this issue:
This thread is made yesterday by another user. I have stopped counting al the threads with this request. I think at least once every week this suggestion pops up by another user. This shows how popular this request really is. So i hope that the dev listen to the people.
It seems like this issue isnt the result of low elo players getting free elo from drops. There seem to be other issues. In the end the result is what you noticed: Team game elo becomes meaningless and no one really enjoys these games.
I made my own thread about this issue:
This thread is already existing for more then 6 months. That shows how bad the current system is for months. I really hope that the devs will quickly fix the main roots of this issue.