The biggest reason would be: do you know a single developer who could have produced this in a couple of hours?
I'm not familiar enough with this animation library to answer that. Someone could be very used to this type of website and just copy paste things they've done before.
Yup, strange to see people still don’t understand LLMs massively speed up coding greenfield pet projects. Anytime you see a bee web app it’s better to assume AI use rather than not anymore.