It could be.., but anyhow if this was their logic, they could focus on how they could reduce tanking which is beneficial for them as well.
Best solution for me to stop tanking (I tank with my 2nd team sometimes) is:
20% quality reduction if you fail to promote
10% quality reduction if you promote
My opinion is that this small change would be a really twist plot of the game and would become even more interesting as you would even compete for 8th position