But you could play the music over SPDIF and record it while playing. I cannot remember having had problems with that. (Until my self-built SPDIF adapter broke...) Also other than stated in the article, MD used its own compression format so you could put 700 MB uncompressed audio onto a 130 MB disc. But in times of > 10 GB storage it makes no sense anymore to use replaceable cartridges. Just put it all on the player. That's what ultimately killed it.
It could have gotten a second life though with MD Data but the drives for that were just too expensive.