You don't need to stack up on keto products to go on a keto diet. However, they can help ease the difficulties of an otherwise highly restricted diet — especially if you're just getting started.
Likewise, keto products that replace traditionally non-keto foods may help you stick to the diet.
Lastly, some products can also help curb your sweet tooth while keeping you in ketosis, and others even provide good amounts of fiber, a nutrient that tends to be lacking when cutting out carbohydrate sources.