Don't they? Or are you saying this site is a good example of doing that?

From a UX experience, I think you'd be more successful if you would let the user experience everything your site has to offer and if they decide to continue (or stay with the site, save their prefs and eventually - become paying customers) - give them an option to create an account, because according to the latest research in UX, any login walls (even the FREE account ones) are detrimental. Check the article I linked above.

Our mobile app doesn't have the demo generator, which is maybe what he tried first? Something we might add in the future.