My thinking is that high rank accounts are actually becoming a little more valuable now that it's more difficult to rank up. You need to put in some real work to do it, people would happily hack an account to cut that out. Imagine if a great poster had their Hero account's password hacked, and they couldn't recover their account because admin wasn't convinced their email wasn't hacked too?
Actually high ranks account are worth way less than before in the sense that they can't make you win easy money anymore now that good paying bounties are nearly extinct. I am pretty sure from what I saw account seller post that the price tag on a legendary account is way down compared to 18 months ago