I think it's because it's not simply a file download but instead keeps on asking for file content or meta data making a roundtrip on each files to cause excessi

I think it's because it's not simply a file download but instead keeps on asking for file content or meta data making a roundtrip on each files to cause excessive latencies against many files. All the tools are basically designed to work on local files and they tend to work bad interacting directly on mounted file systems.