Because zstd is not mature enough. Facebook claimed it was production stable, yet even with 1.5.1 it created corrupt archives at level 16 or above compression. Moreover, zstd is a single file compressor which means it needs a container for all files (like TAR) before initiating compression. I benchmark and observe zstd apart from blosc and many other projects aiming for Pareto frontier, however I find it quite concerning nobody thinks about Pareto frontier in terms of distribution of compressed contents, since compression is only performed once.
7Z is a full featured stable general purpose archival format with more than 25 years of development and track record, and has support for repairable headers, Unix/Windows precision timestamp support, far stronger compression (10-20% better ratio than zstd) and incredible ease of access (7-Zip on Windows and compress/decompress support built into Linux distributions).
Because zstd is not mature enough. Facebook claimed it was production stable, yet even with 1.5.1 it created corrupt archives at level 16 or above compression. Moreover, zstd is a single file compressor which means it needs a container for all files (like TAR) before initiating compression. I benchmark and observe zstd apart from blosc and many other projects aiming for Pareto frontier, however I find it quite concerning nobody thinks about Pareto frontier in terms of distribution of compressed contents, since compression is only performed once.
7Z is a full featured stable general purpose archival format with more than 25 years of development and track record, and has support for repairable headers, Unix/Windows precision timestamp support, far stronger compression (10-20% better ratio than zstd) and incredible ease of access (7-Zip on Windows and compress/decompress support built into Linux distributions).