I just opened a box, that had a SideWinder in it - It looks like it just fills up bobbins - or does it do something else.

Mind you that I have 2 older sewing machines - a Viking from the 70's and a Bernina from the 80's - Bobbins can be filled on my sewing machines

Is it something that is needed in a sewing room. Isn't just as easy to use you sewing machine to fill your bobbins - Does everyone have one of them?