They have some many parts of spinning up/change the infrastructure (Terraform), connect the services (Consul), run the apps (Nomad) but not their own way to tell you how well they do. Also monitoring is quite sticky and high margin. I think it makes sense but have no special insight.
I'm not so sure. There's very little wrong with prometheus or influx + Grafana. We're about due another iteration of logging stuff now we've all gone graylog->splunk->elk->Loki though. (And they all suck)
The thing with Netdata is you don't make compromises on number of metrics and Cardinality as the data stay with the node. Netdata.cloud can aggregate on the fly without storing. Check it out