That's irrelevant to the file formats themselves, however. A simple file format doesn't automatically guarantee a simple implementation, especially for compression algorithms.
Maybe it doesn't guarantee it, but at least a simple format makes it possible.
A complex format makes it impossible to have a simply implementation.
but I think xz won the linux-lzma-archive formats war exactly because it was more complex than lzip, e.g. by supporting more versatile lzma2 format, which allowed to implement multi-threaded compression and decompression (pretty sophisticated things), and better crc64/sha256 hash checking