There are multiple ways to limit tanking ....
If Nordeus is keen to do it they can put in place a bouquet of measures to :

A. Incentivise 1-8 position in the leagues (tokens , excusive stuff , exclusive events blah. blah blah)
B. "Penalize" 8+ positions .

Its a matter of will. When there is a problem , there is always a solution , especially in a virtual game.