Why pointless? All good managers joined to BB only in 1st, 2nd or 3rd season? And all managers who joined in 4th season or later are worse?
And please note, that this tanking as was made by VS, is possible only in small country. In big country team will be relegated and incomes in next season will be much smaller. Other way is to tank in high league in first season, and after relegation use money to promotion in 2nd season and to tank in 3rd season again. But this method is 50% less effective than tanking in small country.
But small coutry vs big country isn't so big problem. More important problem is that manager who joined earlier has big advantage in comparition to others, who joined later (in the same country). Weak manager who joined earlier (and therefore who plays in higher division) still can develop team faster than good manager who joined later.