likewise collecting damages, etc
I think it would depend on the local jurisdiction's definition of the tort. A purchase/refund scheme would not induce Apple or the vendor to breach their app store contract, but it would deprive the vendor of its expected economic benefit.
edit: so who is in trouble here? The person calling for people to do it with their twitter following or the twitter followers? I'm not saying that buying the app and returning it is not fraud if you entered into the transaction in bad faith and with intent to cause damage to the dev, I'm saying calling people to do that is not fraud.
I think the form is definitely fraud but I wouldn't be surprised if Visa went after you for something as well, they need to actually process all those charges and charge backs and it does cost them some amount of money to do so.