I was speaking to a more general monitoring approach where you might want to know p99 latency, request volume, error rate, etc, for each service to use in alert

I was speaking to a more general monitoring approach where you might want to know p99 latency, request volume, error rate, etc, for each service to use in alerting and trending. This is a common use-case for application monitoring that isn't addressed well by a pure tracing approach. If you're looking specifically for the 100% audit trail case, I'd look at DynaTrace or potentially Instana.