The blog post 'PHP2Shell: The Patch Took a Day. The Sites Nobody Remembers Are the Real Risk' by Roberto discusses the complexities and risks associated with PHP vulnerabilities and the security implications for obscure or forgotten web applications. It emphasizes the need for developers to pay attention to older or less maintained sites that could pose security risks, even if they seem inconsequential. The author shares insights and lessons learned from personal experiences in addressing these vulnerabilities.