As long as there is no manipulation of data, positive test rate is truly something to pay attention to. It's not perfect, but neither are total number of cases, fatalities, or hospitalizations. They are all indicators that can be used to understand the trend relative to time. We want them all trending the right way.
You can't assume that less healthy people would be getting tested in April than they are in July unless you have evidence to back that up. Especially with counties making testing more available. Now if local authorities or hospitals are under reporting negative tests that would be a pretty big deal.
My personal opinions are similar to yours - that this appears a reactive one-size fits all response at best, if not deliberate misleading by government officials as a power grab. Not that this isn't a serious issue, but that the last few months a more targeted approach seems more reasonable if the goal is protecting citizens.