What exactly does embossing do?

The store sort of explained that if I did not emboss and I had down old vinyl with say a grout pattern, and the grout area was sunken and the I put new sheet goods over it, the glue would physically suck the new vinyl into the grout lines areas and it could be noticable at certain angles.

The floor in my wife's salon currently is vinyl with a marble effect and slight texture. She is replacing it though with rather thick fiber floor angain with a swirl pattern.

I am trying to detemine if the embossing is really necesary...we rent the place and it adds $200 to the install price. The store guy sort of thought we would not need it and could remove that line item from the stimate....but made no guarantees.