system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why do Hip-Hop/Rap artists collaborate on albums more often than other genres?

Just wondering because I can get a Tech N9ne album with every other song featuring another artist, but go and buy a Rock album with just the guys on the cover.
gpt
It has a lot to do with production process, and just differences between genres. In hip hop, the people writing the music and making the beats are generally not the same people spitting the verses. So if a producer makes a beat, he'll get 3 or 4 different MCs on it to give it more variation or reach a larger audience.

It scales up, too. Top 40 producers will shell out literally hundreds of thousands of dollars to get a popular rapper on a track (listen to that new Taylor Swift song with Kendrick on it for a really blatant example). So you have producers deliberately seeking out multiple MCs or even "buying" verses to make the songs more interesting or more marketable.

Rock music is different. Even commercial rock bands generally try to give the impression that the people in the band are the ones writing and performing the music. So it's often less desirable, from a production standpoint, for a lot of outside collaborators to appear on a rock album. It's also more economical to just have someone else in the band sing if you want more voices. Or somebody's girlfriend. That always works.