There are many advantages, but when it comes down to competing, here's the principal ones:

• Speed: Shopitag is fast, both in set-up and in use for your customers
• Presence: some of your competitors may simply not (yet) be online
• Familiarity: your customers reach your online pop-up shop through the channels they already know (Facebook, your website, e-mailing, FB Messenger, etc.)
• Flexibility: you can run multiple pop-up shops focused on different types of products or promotions, vs. one big, cumbersome webshop

Read more about your shop optimization here.