The cost of going through that list often outweighs the cost of the hardware, by a lot.
And in a lot of cases it's hard to find out if a production application can be switched off. Since the cost is typically small for an unused application, I don't know if there are many people willing to risk being wrong
People always say stuff like this, and I just don’t buy it. It’s not that hard to analyze network traffic to see what does and doesn’t have active connections. When you’re relatively certain, shut it off for a week. If no one screams, delete it. If a month later someone is screaming, it’s their own damn fault for having no docs on something idle 90% of the time.
I've done many things that got new data ingested on a monthly basis. So say 29 days out of every month they would be idle.
Is it worth starting and stopping those kind of things? Probably not?
If you turn off a VM running something like that, because you didn't see any traffic for a day. Are you going to explain how you just shut it down to save a few dollars a month? I would very much like to see how that unfolds