I think they wanted a site refresh, and instead of doing it visually and/or adding features at the same time (people do this still, I think its okay), they likely thought that due to AI assistance it would be easy to actually start from scratch.

Not sure why you couldn't take the "its easy with AI" path and actually refresh the current codebase.

This is hearsay mind you, I don't know how much of their old site is there...