Existing tracing systems (Dapper, Zipkin, Dynatrace, Stackdriver, etc.) already randomize with each hop, and there was a desire to be consistent with the models

Existing tracing systems (Dapper, Zipkin, Dynatrace, Stackdriver, etc.) already randomize with each hop, and there was a desire to be consistent with the models that they already used. It's also more straightforward to implement. There's a discussion about "correlation context" inside of this W3C group called , which maps to what you're describing. It'd be worth reaching out to Sergey (one of the other co-chairs) if you want to find out more.