My single biggest issue with KPIs is that, for the most part, in a large company, one (or even several) metric(s) cannot cover the whole story.
They are useful for very specific targets.
I’ve ended up working towards KPIs which I’ve known have zero relevance to improving service because they are (a) poorly defined (b) irrelevant to the actual problem (c ) force a metric to exist where no sensible metric can.
Unfortunately this tended to happen more often than not.
OKRs have their place. But they don’t sound like something new (KPI rehash) and are wide open to misuse, just like KPIs.