[derefr]

What the parent is saying is that the client has to buffer the entire zip file before they receive the index and can begin decompressing it. "Streaming compression" usually implies streaming decompression as well—importantly because a non-negligible use case for streaming compression is sending streams of compressed data that won't fit on the destination together with the decompressed copy; or sending continuous streams of compressed data that could never reach the end to be decompressed. What the parent is saying is that zip cannot work for these use-cases.