What is the advantage of using Prometheus over ingesting metrics using logs?
Efficiency

If you don't need the file it saves space and trouble to leave it out.  Logs require rotation and retention policies which are nice to skip.

Reliability

Skipping the file avoids issues with the file that could caused lost metrics like a full disk.

Latency

Skipping the file means that you remove latency from disk I/O.  For most metrics you don't care if they show up a few seconds late, but if you're trying to build things to respond to some metric quickly.  You might want to put it on Kafka also.