Albums and three minute songs became a popular format to record in because they could be commodified as a record sales. Novels become the most popular form of creative writing because they could be commodified as moderate sized- and moderately priced book sales. Etc.
The title itself is problematic, because it should be "A brief history of why artists are no longer making a living making popular music." Classical musicians (with notable exceptions) have been unable to make a living recording new music for a long time. Only specific genres were able to thrive during the 3-minute song album era. And now the internet has made that more difficult because we don't need the commodified form -- records, cds -- anymore.
But people can still make money writing music that is bundled with other commodities: movies, games, etc.