Tar is not streamable when compressed with gzip. 4Q supports compression on a per-file basis and thus can support streaming and compression at the same time. Zip also supports compression on a per-file basis, but it requires an index and thus is not streamable.
You can stream zips if you don't use compression, and you can use compression on files small enough to hold in memory. I work at Barracuda Networks, and we actually do this every day.[1]
