What you are describing isn't rolling your own (i.e. writing your own code) - it's installing pre-built software which was OP's point. And Shopify being the mo

What you are describing isn't rolling your own (i.e. writing your own code) - it's installing pre-built software which was OP's point. And Shopify being the most common platform now, and quickest and easiest to get up and running, is probably why they used that as an example (i.e. you could have a decent looking matcha-tea store setup within an hour with all the payment methods you want).