This is not unlike what we've been doing for years. We generate billions of log lines like this daily as json and inspect them with splunk. By having consistent values across log lines, we can query and do neat things. "What was our system timing in relation to users who have feature x?" "What correlations can we find between users whose requests took too long and were not throttled? -> ah, 99% of those requests show $correlation_in_other_kv_pair!"