This explanation is the one I’d heard before and it makes a lot more sense to me. My memories of the 90s is that underground DJs were happy to share their music

This explanation is the one I’d heard before and it makes a lot more sense to me. My memories of the 90s is that underground DJs were happy to share their music¹ with others and wouldn’t have sullied their vinyl collection by ripping off the labels. Maybe some DJs were territorial but most would be proud to show off the fruits of their record hunting. ¹ So much so, that they were far less willing to share the decks.