Of course. Two reasons:
- First get notified when an integration is failing
- second, I want to detect if one of my grid surge protections gets triggered (power outage on one of the mains groups). That is always possible as both HA and my network run behind an UPS.
For the second use case I want to avoid false positives.
In order to detect this reliably, I monitor combinations of devices of different integrations, on the same mains group. Additional I like to detect issues with the integration owing these monitored devices (typically HUE, ZHA, MQTT).