一个问题，博客需不需要 Redis？

前几天写的laravel-blog被老外看到了，然后问我了一个问题：

Why do we need Redis for a blog system? If this is truly a fast blog it should be fast just using a database, no?

我简单回单了一句，为了缓存，提高速度，结果他不依不饶：

Depends on the use case. What are we caching? Indexed queries in a relational database are usually very fast. Adding Redis makes for a more complex stack so it must be motivated. Are we not just talking about saving lower single-digit milliseconds here? And to do that we add a hard dependence on Redis, making hosting more complex, error-prone and expensive. I love Redis and use it when it's appropriate. I also love relational databases because they solve complex use cases in a performant way. I asked why it is motivated to add Redis for a blog engine, and I just get a hand-wavy "for caching" as an answer. What do we need to cache and why can't that problem be solved without the need for a Redis cache?

回答了一长串，具体看这里：here 截图：.

所以到底要不要缓存，我该怎么回答？强大的 V 友帮帮我