I have been told that eCommerce sites always needs an application. Why exactly is it?
Because nobody wants to search and see all the products in an eCommerce site. They basically look for a single product or single product category so an application totally serves their purpose.
Most marketers use apps for their eCommerce site because its easy for their clients to navigate and locate their respective products through an app.
eCommerce needs an app for their beloved users because it serves as a one stop shop for their product and services.