You're still on the same US-diversity train but there's nothing in that comment to justify it.

There are other many more layers to a tourist's cost/benefit analysis than just culture. Some of those layers will be common to the entire US:

- exchange rate between USD and their home currency

- affordability might vary across the US, but perhaps the consider even the cheaper places to be too pricey (the US is indeed a very pricey destination compared to much of Europe)

- the customs & border people deter tourists from visiting, no matter where in the US they want to go

- the US is a long flight away for many people in the world, whether they're going to Seattle, LA, NY, or Miami.

OP might be absolutely enthralled by US cultural diversity and still make the exact same comment.

But you don't know that. Maybe op has done multiple cross country trips across America. Maybe they've only been to NYC and Disneyworld. You could have asked them, but you didn't!