Yes, I agree that starting by caching when you have something that could be a lot faster by just doing smarter things with the code in the first place is not the right path to go. However, my point was just that there are many levels of caching going on in a computer and often times developers aren't even aware of them.
For example, how many people write their own file system or memory based caching scheme or jump right to memcache to cache database queries, when they really could just cache the whole page using Varnish or Squid? Just understanding that there are those various levels of caching from processor to memory to filesystem to web server to opcode caching (or JIT'ing) to memcaching to database caching. A lot of developers just flat out don't understand that all of those things exist and what to do make the most of them in the right situations.
For example, how many people write their own file system or memory based caching scheme or jump right to memcache to cache database queries, when they really could just cache the whole page using Varnish or Squid? Just understanding that there are those various levels of caching from processor to memory to filesystem to web server to opcode caching (or JIT'ing) to memcaching to database caching. A lot of developers just flat out don't understand that all of those things exist and what to do make the most of them in the right situations.