Boxers use jumping rope to practise being on their toes and moving about. This is the reason it is actually not bad for your joints. When you impact the floor with the front ball of your foot it acts as a suspension, absorbing the impact.
This is also the way I started running in recent years. I used to get iliotibial band syndrome from running on my heels, but when I started running by impacting the ground with the front ball of my foot the ITB syndrome almost went away. I haven't had pain from it since.