Do we even know ST's streaming metrics, or the economy of streaming in general? I have to believe some basic input/output still matters.
While I'm not sold on the metric, there is one out there that steadily showed that Discovery was very popular over the first three seasons. I'm sure that someone here can point to the actual name of the service, as I can't remember it off of the top of my head.
Thing is, they can't even sell STD to a wider audience after they decided to re-tool it. Those numbers may go down, they're not going to go up.
In the long history of TV, not too many shows gain audience as they run. So even if CBS' numbers are eroding to some degree, it would be expected. In Star Trek's case, Viacom knows how many people are subscribing and what they are subscribing for by monitoring viewership. And the numbers being kept internally is nothing new with streaming. They don't owe it to us to make their internal metrics public.
That there's nothing REALLY in need of improvement
Improvement in whose eyes?