> What is the value proposition exactly

Having a career.

It's very rare for someone to last decades as a performer in the entertainment industry, and online content moves faster than most. You don't want to suddenly have no audience age 35 with zero skills or experience outside making potentially niche YouTube videos.

This typically comes from chasing after higher sources of recognition/prestige/clout, and it's especially prone to happen when you have a background in the "traditional" industry and saw the whole endeavor of producing Internet content as a stepping stone. "Finally, I can run a proper show with real production values", they say. Emulating an idol is the goal, but there's often no particular benchmark guiding it and their creative role suddenly shifts towards managerial elements, so the final product is invariably worse than whatever they did before. Plus the impulse to do it is pretty much always an indulgence running counter to market trends.