[thaumaturgy]

Yeah, I can't figure out what they're talking about there. There is no "SaaS ecommerce platform" category on BuiltWith (that I can find); none of the subcategories under the eCommerce category on BuiltWith has BigCommerce near the #2 position (https://trends.builtwith.com/shop).

They do note later in their document that their competitors include Magento, Shopify, and WooCommerce.

I almost scrolled by and didn't care except for your comment, which surprised me quite a bit. The number of Shopify, WooCommerce, and Magento sites I've had to do some amount of work on over the years more or less tracks with BuiltWith's stats. I've never worked on a BigCommerce site.