Easy to say but much harder to implement. For example, if you communicate with another service, a few network errors are usually not actionable and you'd have some fallback mechanism in you code. But tons of network errors (e.g. > 20%) is a problem that needs to be fixed now. So would you log the network error or not?
Sure - but then the developer-facing "log" is the New Relic interface, and your instances transmit failure information to it via some API (I mean I suppose you could have one program output a plain-text log file and then another program or service parse that to figure out how many errors were happening, but you wouldn't do that for any other kind of inter-system communication).
Easy to say but much harder to implement. For example, if you communicate with another service, a few network errors are usually not actionable and you'd have some fallback mechanism in you code. But tons of network errors (e.g. > 20%) is a problem that needs to be fixed now. So would you log the network error or not?