In addition to what others said, there is no guarantee working at a startup is going to give you broad exposure to all the skills you will need later. A well designed and delivered program can do this.
Some grad programs similar to this one also lead up to a capstone course that brings previous students back and gets them exposed to new graduates. This greatly improves exposure and success.
There's no guarantee a "well-designed" program is going to do this either. FWIW, I quit my PhD at CMU. I worked on self-driving cars as a student and now I do it again as an employee (and did many other things inbetween). Startups are better.
Some grad programs similar to this one also lead up to a capstone course that brings previous students back and gets them exposed to new graduates. This greatly improves exposure and success.