And now I'm going down the rabbit hole of looking at what's the difference between Graphite, InfluxDb, ...

I played a lot with Nagios and RRDTool and glanced at Cacti at the end of last millennium, and played a little bit with Prometheus the other year, and to me these all seem like basically RRDTool on steroids.

I'm not saying they're not an improvement, it's not a bad thing to be RRDTool on steroids, but the hype seems to be saying that everything is brand new when everything is iterative improvement on solid concepts.