The document discusses some of the challenges of practicing Site Reliability Engineering (SRE) on AWS. It notes that with over 200 AWS services and frequent updates, it can be difficult to keep up with the changing optimal solutions. When implementing service level indicators (SLI) and service level objectives (SLO) to measure reliability, the many AWS services need to be considered to determine how to define and measure the SLI metrics. The document also emphasizes that while SRE practices like SLOs are important, not all companies need to implement everything described in the SRE book from the start, as Google-scale reliability may not initially be required for all services and businesses.