But if you hire that musician, you can create more products you can license. The worker generates more revenue streams for you. This is why streaming companies are leasing soundstage space, to create more stuff to license themselves.
But not all types of music are equally in demand. If consumer tastes change, it would obviously make sense to layoff musicians trained to make music for a genre that nobody wants to buy anymore.
That's one way of thinking which IMO is a cold way to look at the world. I would say its just simply nicer to retrain your staff to meet your goals versus cutting them off and finding new staff all the time. Too bad nice typically goes against profits in this economy.