The total amount of consumer products that can be sold is bounded by consumer income. Advertising mostly moves demand around; it doesn't create more demand, at least not in the US where most consumers are spent out.
Think of taxing advertising as multilateral disarmament. Advertising is an overhead cost imposed on consumers. If everybody spends less on advertising, products get cheaper. Tax policy should thus disfavor zero-sum activity.
Don't discount the opportunity that "advertising" presents to smuggle in a bunch of expenses that are either zero or negative on ROI.