Some would simply call it an evolution of style, and others might call it a sellout. I’d like to hear your examples of musical acts that changed so radically over time that you’d consider it a sellout.
My example would be Jefferson Starship. Their first album was “Blows Against The Empire”, which was about hippies hijacking a starship. https://www.youtube.com/watch?v=HzclibWeXM8&t=1126s
Grace Slick was the first person to say “motherfucker” on television when performing their material.
They went from that to shedding personnel, renaming themselves “Starship”, and making pop music. https://www.youtube.com/watch?v=IDI2WQJyE7I
What are your before and after examples that you consider a sellout?
The first three albums sound nothing like what most people recognize as Journey.