Hi there, No you do not have to hold the machine at the bottom, but it does mean you gain extra height by having the fixing at the bottom of the machine, and this can prove very helpful when knocking in long posts as you need to have the machine positioned directly above the post and straight and in line to ensure the post is driven in straight and level. You can hold the machine via the top bracket if you wish and also you could hold the machine via the bottom bracket to break concrete if you had just a small amount to break and then you where back to fencing. Please do not hesitate to contact us if you require any future information.