Recently a very handsome, very talented local artist tried his hand at stand-up. He crushed. My friend leaned over and said "That's not fair! He can't be good at this too!" What? Why not?
It makes sense that if you're skilled in one artistic area you may excel in another. Artistic endeavors are a different mental playing field than those of business, sports, retail, etc. But those who thrive in art may starve in retail. They could be horribly untalented in customer service. Restlessness might constantly chase them back into their studios. There's a trade-off somewhere.
Also, if it suddenly came to light that one of your heroes had additional talents it would only increase your adoration for them. If you discovered Louis CK was also an amazing comic illustrator what would you think? Why is it so much harder to admire a peer than to envy them?
Envy is described as a sin, but let's remove that cringy religious connotation and simplify: Envy is a behavior with no positive outward outcomes. Actions towards others motivated by envy are fully expected to have a negative effect. Confidences get broken in multiple ways, skills become shrouded with doubt, collaborative growth drifts to impossible. Envy flings words behind backs with the secret hope of tremendous failure falling on their figure of choice.
Perhaps it's a necessary evil. Maybe they all are. But they sure are tiring.