OctetString Engineer Says ‘Caching is Evil’

Ran into this comment which took me to above article. Besides the basic marketing stuff, the thought/comment did go into the core issue of why cache.
The idea of cache and cache management arises from the basic tussle between performance and data freshness. If you need better performance you will go with cache (well designed to have good cache hit and low cache miss) while if freshness is important cache may not be your cup of tea (unless designed so that updates flow into cache from datasource).
With regards to that, the cache has its place in identity management for data that for which the cache expiry or update speed is much higher than rate of data staleness (like first name, last name, email id, contact information) while it would be not so good viseversa or if freshness of data overrides performance requirements.