For one, it’s infuriating that all of the music in my house stops if I want to listen to a podcast. Refuse to even try Spotify podcasts for that reason alone. I often have quiet background music on with a podcast in the foreground.
So the issue isnt really that you want to have podcasts and music be seperate. It's that you want to be able to play two audio streams at once from Spotify.
That isnt a supported feature. They would ask you to get a second account if you want to do that.