dtgreene: Also, ar and tar do not actually compress files; all they do is combine multiple files into a single one. (It is very common to compress tar files with another program like gzip or xz; so common, in fact, that such files are more common than uncompressed tar files!)
Ummm... How is this relevant? The unix OS was originally designed by breaking functionality into pieces, then you could mix and match, so each utility did it's own subset of jobs, but it did them VERY VERY WELL. Sort does sorting, tar/ar does archiving, Gzip/Bzip2/7z do compression, etc. This means compression isn't tied to the format. Zip will always be tied heavily to it's lz77 and have it's weak encryption model, while with tar if something good like xz comes along, you just compress it via a pipe and it's done.
Lack of random access might be an issue for really really really big tar files, but otherwise it's not really a limitation at all as far as i can tell, although mentioned with the 8Mb to 2Mb/200k, the amount of extra space saved (
in many cases) probably easily makes it worth it. Although if you break down tar's name (
Tape Archive)... yeah there is no random access, not precise enough to access a single file. So *shrugs*