You get the same product recognized on any screen
Before, you might name a product one way in search, another in stock, and a third in reports, with each system treating it as a different item. With the naming rule written and applied, the same product shows up the same way everywhere someone looks for it, without wrong stock counts or a sales report that doesn't match what actually left the store.
You list a new product the same way, no matter who's listing
Without a written rule, you and whoever else listed a product each decided the name order and what counted as a variation on your own, and the catalog kept getting less consistent as the person listing changed. With the rule written in a way anyone can follow without asking, a new listing already enters under the right standard, and the rework of fixing names after the fact goes away.
You stop confusing a variation with a new product
You often end up listing a size or color variation as separate, or mixing in an actually different product as if it were a variation. With a clear test between the two, each item lands in the right place from the first listing, and the catalog count gets closer to what's really in the store.
You get ready to standardize the whole catalog later
If you try fixing the whole catalog at once, without a rule set beforehand, you tend to stall on the same decision repeated product by product. With the naming and variation rule already written and tested on a real product, the store has a standard ready to apply to the rest, and bulk standardization moves faster, because the naming decision is already made.
You write the rule down instead of keeping it only in memory
Even when you have a right way to name things, it usually only lives in the head of whoever has listed products the longest, and it gets lost when that person leaves or forgets one specific case. With the rule written in a few lines, it keeps working even after whoever wrote it stops listing products, and the store ends up with a standard that outlasts whoever does the job.