There's no point in buying an expensive domain name for a company that may not survive past the startup stage.
Note: a large swath of web users don't even understand the concept of a domain name or address bar...instead they google terms like "Gmail" and "YouTube" thinking this is how they are supposed to visit web sites.
What's more, tech-savvy users wouldn't think twice about visiting domain name ending in ".io", ".ly" and so on. (Hence their proliferation.)
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I can't help but wonder if this article is some kind of prank--it's far too ill-considered compared to Graham's usual standards.