Yes, you can use block planing tools on MDF boards. However, the kind of block plane you use depends on the thickness and configuration of the MDF boards. A thick board might require you to use low-angle planes, as they help you perform both smoothening and shaving processes in an adept manner. Only the right block plane will give you the desired results. So, not every block plane on MDF boards is fitting to work. You need to look for compatibility before working. There may be less to more consequences, depending on the work performed.