I do not agree with this. when a newbie trying to buy high rank account and join the signature campaign. but the poor quality posts and eventually account got banned. better try from the beginning.
And a LOT of the accounts are obvious that they were farmed/sold. Sadly account farmers have a ton of low quality post in most cases things like offtopic threads what was your last drink, what was last music you listened to, etc. Basically to raise activity level of account and it becomes obvious it was sold.
And other way is some long period of time without post's and come back posting with a different style. So again becomes obvious. So I would not count on buying if you want in a "good" signature campaign. You really need to start one and have high quality posts from beginning.
I know some will always want to try to fasttrack it by buying. But I think a lot of them end up banned for insignificant posts or some negged for being part of buying/selling of accounts.