A plain ICMP check asks one question: does this machine answer? No ports, no credentials, no assumptions about what runs on it. When the answer changes, your escalation policy runs.
Ping answers a narrower question than an HTTP check, and that is exactly why it is useful. It separates "the machine is gone" from "the application on it is broken".
Know a box has dropped off the network before someone opens a ticket about the thing running on it.
Routers, switches and firewalls rarely speak HTTP but they all answer ICMP.
Appliances, NAS boxes and hardware that has no port worth checking still tell you they are alive.
Pair a ping monitor with an HTTP monitor on the same host. If ping is up and HTTP is down, the problem is the application, not the machine.
Round-trip time is stored on every check, so a slowly worsening link shows up as a trend rather than a surprise.
Monitor an office line, a VPN endpoint or anything that just needs to be reachable.
A ping monitor is a monitor like any other. Draw from its down port and the policy runs exactly as it reads.
Require several missed replies in a row. Networks drop the occasional packet and that is not an outage.
Notify a channel first, wait, then page whoever is on call if the host is still gone.
An HTTP action step can hit an endpoint that power-cycles or reprovisions the host before a human is involved.
Every outage is recorded with its cause and duration, alongside your other monitors.
Three monitors are free forever. Add a ping check and draw what happens when it goes quiet.