The SEO for e-commerce requires an initial investment that will results in organic traffic (therefore free) in the long run, contrary to paid channels in which the disbursement of the budget cannot be interrupted. The most experienced users have already realized for a long time that Ads shown during web searches could actually be misleading. Are those incessant sponsored products actually convenient?
During the purchase process there are several stages in which you might retrace your own steps: you re-evaluate the reasons to why you might purchase the product, the use you would make of the product, you compare offers, discounts… The user is hunting, just like any Wolf that runs an e-commerce. Throughout these steps, despite the advertising strategies, a potential customer will always go back to where they started: the search engine. The organic result will always be there, where he found it in the first place. That’s why SEO for E-commerce is fundamental for your online store.
On the sponsored one, on the other hand, who can give such certainty? No one, because the user could have changed the place from where the web search began in the first place, or he might have refined the terms of the search.