They need something they can check easily so the team can get back to work. It's hard to find metrics that are both meaningful to the business and track with the work being asked of the team.
Its easy to fake one metric, it harder to consistenly paly around 100 of them.
(But then it’s no longer KPIs probably, as one looking at the data needs to recognise that details and nuance are important)
You can look at revenue and decide "hey, we have a problem here" and go research what's causing the problem. That's a perfectly valid used for a KPI.
You can do some change by something like the Toyota process, saying "we will improve X", make the change, and track X out to see if you must revert or keep it. That is another perfectly valid use for a KPI.
What you can't do is use them to judge people.