> After all, sales is sales and if you don't have repeatable sales you probably don't have much of anything.

That's right, but you're missing the key that it's a necessary, but not sufficient requirement. When the pool of investments is 90% with ARR are honest and straightforward, then it's good to use ARR as a metric. But when the pool changes to 50% or less who are honest (as Goodhart would predict), the metric loses value.