When creating a new campaign for a shop's promotion of jackets, shoes, and handbags, why is it recommended to create separate campaigns for each line of merchandise?

Separate campaigns are recommended to allow for product-specific messaging and individual ROI optimization. Jackets, shoes and handbags have different margins, different seasonality and different customers, so they deserve their own budgets, targets and ad copy. Splitting them means each line can carry a target that reflects its own economics, budget can move to whichever line is performing, and reporting shows clearly what each is contributing rather than hiding it inside a blended average. The counterweight is worth remembering: splitting too finely divides conversion data into pools too small for Smart Bidding to learn from, which is why single-keyword ad groups and heavily fragmented structures are discouraged. The practical rule is to separate where the business economics genuinely differ, and to consolidate everywhere the difference is cosmetic.