Yup, I've had more than one current Google SRE state "You can have my Borgmon when you pry it from my cold dead hands.".

Borgmon may be dead in the eyes of some people, but I know for a fact that it's still the only thing monitoring core and critical systems.

Most of the problem with Borgmon, IMO, is the cruft that has built up over the decade+, and neglect due to the Google pattern of "The new thing that doesn't work, and the old thing that is deprecated.".

The difficulty at Google is that developers are rewarded for writing new and shiny from scratch, rather than fix the old but working systems.

This isn't always a problem, as some good things can come out of starting from scratch. But sometimes they throw out too many of the good ideas, in an attempt to be fancy and new.

I have heard unflattering things about it from a few different ex-Google SREs, specifically about the macro system and it being cumbersome to use.

You will note that Prometheus explicitly does not have a macro system.

Oh sure, I was responding to the OP stating that criticism of Borgmon was more a meme than reality.

It wasn't meant to be commentary on Prometheus(which I quite like) at all :)