So you mean they are not interested in the division rewards (most likely 100T) but they tank only to stay competitive for top ranks in associations? Maybe there are a fraction of users like this but I doubt it is the case for most.
As for me, I never tanked despite having been gutted to overflow point many times with the game in the past; I just left my team with a decent formation and line-up and stopped playing. Maybe some people might tank out of revenge just to piss off others but it is not worth the effort unless this person gets decent entertainement doing so.
It seems that there are differences (both good and bad) between servers because all this time I played I never faced certain things that others been complaining a lot, like for example, the problem of tankers, but I faced other problems that others were not complaining much like poor auction lists and even poor scouts list with respect to what type of players I was looking for. I don't even know which server this account is currently on, but in the past, I had a serious scouts and recommendations buyer (Andalucia) as opponent only once in the League with this account. So, there was no serious reason for people to tank say to put some distance between them and heavy-token buyers.