How would you recommend doing it? Which company are you referring to?

The company I was thinking of was Apple.

I think interviewing people is a good idea. The fact of the matter is at the "idea" stage you don't have enough information to present to people to really give them a feel for if your specific product is viable. But by interviewing a fair number of people, you can understand what their legitimate needs are and what they're willing to pay for it.

Of course it's not foolproof, but I think it will actually be better than the approach given in this blog.

You can still test ad copy and landing page copy that promises a future product in exchange for an email address.

I'm not recommending that companies do this to figure out how to acquire customers.

I'm saying a person should do this to help determine whether an idea is worth pursuing.