In the mid-2010s, distributed tracing was a good idea but an operations nightmare. Zipkin, Jaeger, X-Ray, Datadog, New Relic, Dynatrace — each had its own SDK, its own data format, its own propagation headers. If a company started with X-Ray and wanted to switch to Datadog, every service's instrumentation code had to be rewritten from scratch. Tracing libraries were buried deep in business code, so the cost of changing tools exceeded the value of using tools. This vendor lock-in was the biggest obstacle to distributed tracing adoption. OpenTelemetry solved this through standardization, and ADOT is AWS's official distribution of that standard.