Anyone here worked with “web-to-print”? Trying to understand it better

I recently came across the term “web-to-print” and was curious how it actually works in real-world use.

From what I understand, it’s basically a system where users can customize and order print materials (like business cards, brochures, etc.) directly through a website without needing to go back and forth with a designer. Seems like it’s used a lot by print shops and companies with repeat design needs.

I’m wondering how flexible these systems usually are like, can you fully customize designs or is it more template-based? And is it mainly useful for businesses, or do freelancers/small creators benefit from it too?

Would love to hear experiences or examples from people who’ve actually used it.