Hmm, I'm not sure. Seems as though users just provide the content, rather than being allowed to actually 'build' a site from TailwindUI components.
One of the premium features is the custom domain which lets users have a website. Hence, the product is generating money on the premise of building a website for you that’s a completely new entity which makes me think this does in fact qualify as a website builder.
From the licence:
You can:
[snip]
- Use the Components and Templates to create unlimited End Products for unlimited Clients.
- Use the Components and Templates to create End Products where the End Product is sold to End Users.