>why apple doesn't have some sort of .app.gz "special"
In addition to other fine explanations provided, it did. The defacto standard was ".sit.hqx" -- BinHexed Stuffit archive, both third-party tools that survived into the OS X era. Disk Images came about when Apple finally realized the pain of delivering Mac apps over the internet.
Also, since I'm posting, OS X should really set the H attribute on these dot files when writing to a FAT drive, rather than relying on Unix shell convention.
Ah yes, good old .sit.hqx—compress something and then bloat it back up by converting it to ASCII. Luckily macbinary (.bin) took over at some point so that resource forks could be encoded without resorting to ASCII.
And you're right. Apple should definitely set the H bit on FAT volumes. Then no one would even notice.
In addition to other fine explanations provided, it did. The defacto standard was ".sit.hqx" -- BinHexed Stuffit archive, both third-party tools that survived into the OS X era. Disk Images came about when Apple finally realized the pain of delivering Mac apps over the internet.
Also, since I'm posting, OS X should really set the H attribute on these dot files when writing to a FAT drive, rather than relying on Unix shell convention.