Throwing hardware at a problem means the writer failed to use his sysadmin staff to do basic capacity planning while there wasn't a problem.

The writer is Jeff Atwood, who runs Stack overflow, a web site that has become quite popular since it launched this year. For sites like that, I think the best approach is to start small (i.e. cheap) and expand as needed.

If you think otherwise, tell me: how would you do capacity planning for a new website with an unknown growth curve?

You concentrate on CPU. Many web apps, including probably the one that I am looking at now (stats from the live system are still pending...), could go faster with more and better caching. I.e. more memory on the web or D=batabase tier. That's hardware too.