Dog collars - stitching

Do dog collars need the edges stitching, or is it optional if you're only doing a single layer of leather (about 1.8mm thick veg tan) ?

I'm guessing it's used to retain shape when the collar gets wet ?

it's only for a little teacup Frenchie so there won't be too much strain on it, I was thinking about 30mm wide, with a narrow riveted band to thread on name lettering.