ktmf01

Currently archives often store audio uncompressed, in broadcast wave format. This results in much more e-waste, shelf space required etc. But they can't switch to just any lossless codec, they need one that can still be decoded 50+ years in the future.

The old specification document didn't specify everything, you needed to read the source code or compare with a working implementation. Will people still understand the programming languages current implementations are written in then? We don't know. So this document should be stand-alone, so one could implement a decoder from scratch (without any other reference) in the future.

With this document, archives can more confidently use FLAC to compress audio and thus work more efficiently.

Opus (or other lossy codecs) try to minimize the perceptible loss. The phase can be completely different, so compressing the difference results in the same size as compressing the original... But you'll need to store the opus bit too.

There are several such codecs however, with a lossy and a lossless part. Not because it is easier, but for compatibility. DTS HD Master Audio is one of them: it has a backwards compatible DTS core.