Sufficient = enough for normal use. My point was that people tend to get worked up and spend time on caching strategies when there's no need for the vast majority of sites.

Even with caching, I suspect Apache would fall over if I got slashdotted.

I agree there is a balance between sane and insane efforts at caching, but I disagree that no caching is a viable choice. Apache and Wordpress with no caching on a smallish VPS will fall over really quickly. This is unacceptable when you can get huge benefits very easily by installing a widely available plugin like WP-Super Cache or WP-Total Cache. It's almost no work to get that set up, and will help you survive a mini-slashdotting. That's going to let you serve an order of magnitude more traffic than usual.

An easy solution like those plugins is such a big win for so little work, I just can't agree with "it's good enough for normal use". The last thing you want is for your blog to fail when you are getting a traffic spike.