Hi Khoi Le,
I believe this was down to the Shopify aftersales and product handling having many more options for marketing and stock management. This particular client didn’t use a fulfillment center however I have integrated this for other clients who did.
The biggest benefit for this was it allows Shopify to become the hub for their products meaning they can link it with many other platforms ie: Amazon, Facebook etc and manage it all in one place.
Drop me an email chris@clickyclicks.co.uk if you would like to have a quick call to discuss in more detail.