Tanking is a way of "defense" for 35T players vs token buyers/farmers.
Tanking also gives a 35T manager to involve in training, developing young players and keep them for some more seasons in the team.
This is a very interesting part of the game and it's pity that so many managers cannot play with it as they lack of sources.
As about my team (the main one), I decided to stay/tanking every while, the latest period, as a disagreement with the new league draw.
It's my protest and future way of playing unless they 'll bring back the mixed q leagues or they 'll give some kind of motivation to higher q league winners/competitors.