Old Lady were unwilling to pay excessive wages
The Serie A club were believed to be close to securing the services of the Sao Paulo starlet, but the 17-year-old has now opted to join Chelsea instead.
"We're actually proud that we haven't signed Piazon under these conditions. It would have been unethical to pay a minor a salary in the region of €1 million (£860,000) per year," Marotta was quoted as saying by Tuttosport.
"What would his future team-mates be thinking? Players who have yet to sign a professional contract.
"It's hypocritical to argue that players earn too much money nowadays and then criticise our decision not to meet Piazon's demands."
Chelsea had considerably less problems with Piazon's financial demands and were quick to seal the deal after Sao Paulo accepted their €6m (£5.2m) offer. The attacking midfielder will join Chelsea when he turns 18 in January 2012.