If i bought somebodies account would i be able to put the Qi & Posts onto this account? Thanks :3

I can already answer: Nope.

why isn't this allowed?

Well, basically, account selling isn't allowed at all. And TSA's only do Qi transfers for emergencies, not personal use.

If you payed them a lot of money they might do it but this is hindered by the fact that Tsas are censored and I doubt you'd ever have enough tc to persuade them.