Nonetheless, those outdated assumptions linger and the irrational fears are widespread and easy to exploit. And that is exactly what is happening, every time a new gtld is opened.

You want to use Amazon as the example? It's a terrible example, because Amazon are savvy. And yet, it turns out, even they do own amazon.biz and amazon.info. The worthlessness of those namespaces is evident: it didn't even occur to you to check them!

Amazon didn't register those for the SEO; it's a pure defensive registration.

Feel free to write to Jeff, tell him to let those registrations lapse 'cos he doesn't need 'em.