I don't think Tanking is cheating.
I think there is little logic in not wanting to try and get promoted. I understand some want Champions League football, but I'd rather play at the highest level possible every season. If that means I get promoted in 7th place, well that has got to be better than another season in the lower level.
If you don't think you have enough Tokens to challenge for promotion, save them for a season but still try to get promoted with your side. If you miss out then you have a nice arsenal of Tokens to make a go of it the following season. If you do get promotion you will still have a nice arsenal of Tokens, but at a higher level.
I have no problem with Tankers however. I have got myself a really strong team by watching videos and doing surveys etc.. That allows me to have a team better than everyone in my league for most seasons, unless there is a Token buyer in my league, so that could also be seen as cheating as I am using the videos to boost my team.
Its just a game at the end of the day, have fun with it, but don't take it too seriously.