I'm speculating that your vendor may be referring to adding sulfite prior to AF to stun the wild yeast / microbes prior to pitching your selected yeast strain. If that is your question, most folks do that, but not everyone. I am one of the latter, although all of the grape wine that I do is from frozen must, and my yeast is pitched while the must is warming and quickly takes over the fermentation as temps get in range.
If you are questioning the use of sulfites as a microbial inhibitor and oxidation protectant in finished wine, then @pip is on track, though a bit dramatic (LOL). AF naturally produces nome sulfites, but in much lower concentrations needed for protection. There are winemakers who introduce no additional sulfites, sanitation practices must be perfect, and the wine typically should be consumed much earlier. Personally, I would never advise anyone to do this, but it is certainly your choice as the winemaker.