We're not talking lossless. The comment above specified Opus-encoded OGG, which is lossy.
For example, I converted my music library from MP3 to OGG Opus and the size shrank from 16 GB to just 3 GB.
And if converting from lossless to both MP3 and OGG Opus, then OGG does sound quite a bit better at smaller file sizes.
So, the argument here is that musicians are underselling their art by primarily offering MP3 downloads. If the whole industry would just magically switch to OGG Opus, that would be quite an improvement for everyone involved.