I think you're right and I get the underhanded logic behind this, but because they are holding my funds, it has made me less inclined to spend any of my money on Tradesy. They are already getting a cut from my sales and I'm already forced to take out 3% for paypal since they don't cut checks. Why should I give Tradesy any more of my money when they deliberately hold it hostage for no reason? Especially when not too long ago, it only took about a day for my earnings to hit my Paypal account.
I still like Tradesy, don't get me wrong, but this ambiguous language of "21 days" and "3 to 7 days transfer" puts a really bad taste in my mouth.
EDIT to add: I don't shop on Tradesy and I'm currently waiting on my earnings to hit my Paypal as we speak.