Tar is really great for its intended use case (archiving files to tape, with the constraints of late 1970s computing power), and kind of weird in basically all other uses. The block format wastes tons of space unless you compress it with run length encoding (which is why .tar.gz is so common). It's dirt simple but also kind of brittle. Its data model is not really a good fit for storing things that don't look like posix files, too much metadata in some ways while missing other kinds.