In fact, rather than fake file or file segment, corruption of a file segment is more common in partial file transfer.

Without tree hash (or some equivalent mechanism), a single file chunk corruption will not be detected before the entire file downloaded then found corruption so has to be dumped.

People should have at least tried out some of the p2p software that have implemented partila file transfer (e.g. eDonkey, etc), and get some first hand user experiences before jump to argue about whether 'partial file transfer' is necessary and how it should work.

It's quite comfortable to say, that once you've tasted a p2p software which based on 'partial file transfer', you would never want to go back.