Risks of publishing the computer serial number on the Internet

I'm searching used Macs to buy in eBay. Some of the offered items show the computer's serial numbers in screenshots and/or plain text. Reading the Q&A https://apple.stackexchange.com/q/91493/21950 , we see this snippet from EveryMac.com (emphasis on the original): > !enter image description here Why not? What are the risks of buying a Mac whose serial number *has been shared on the Internet*?