Could they even be off by a factor of 10?

I used to work in Data Science. I definitely agree with this sentiment. Sometimes we did statistical calculations of 'confidence'. Personally, I rarely felt confident, due in part to my constant OCD / skepticism. Question for people who know statistics better than I do: what does accuracy mean when there isn't a known "true" / standard value? What's the precision of a measurement when things are an order of magnitude off?

The article mainly talks about attribution. Another possibility is for some non-trivial portion of data to be systematically missing altogether. Data which isn't a randomly distributed sample, but a particular characteristic.

but all these numbers are actually good for (maybe) is relative comparisons

I also agree with this. I guess it's okay for metrics to be wrong? As long as all the metrics are equally wrong in perfect proportion? This is why I also like to track the proportion between metrics, as well, as an internal consistency check. My mathematical intuition is that if the metric in question is a monotically increasing (growth) / decreasing metric over time, there will be a interval of time which this relative proportion is useful, after which the metrics, growing at different rates, will diverge to incoherence. Of course, models are not perfect representations of the world, and merely reductions to the key components. To give a concrete example of a model where things look good in some narrow domain, but breaks down. I wrote a physics wave propagation simulation. Instead of actually implementing the Wave Equation which is too much math for me, I used Hooke's law as an "approximation" if you can call it that. It's a good enough visual approximation, but there will is a critical value at which the system implodes or some fuzzier value at which things no longer look "unnatural" to say the least. Then again, Newtonian physics breaks down after a while too.

Also, when the model IS outputting the right answers, it could be for the wrong reasons. Companies will spend money on a particular thing, which they correlate and assume causes growth. For example, a particular marketing campaign. It could just be coincidence / fluke. Does Descartes' evil demon like trolling analysts?

I'm also a self-proclaimed minimalist: materialistic, and beyond. I'm curious what's people's experience with "hoarding" metrics? Given how hard it is to have accurate metrics, I feel reporting should be reduced to a small set of metrics one can be confident about, rather than a large set of metrics, none of which one can feel confident about. If I ever work on my own startup, that's how I'd run things, or so I hope. Maybe businesses gets pressured, to feel productive, to build confidence with employees, or by their investors to crank out metrics? I'd love to hear your stories there.

The article talks about having no idea what we're talking about. Sometimes we have no idea what we mean, ie: Semantics. A metric which we describe qualitatively in English can drastically differ in value based on how we formulate a query / computation. Maybe basic English sentences are not Turing complete, even. This notion doesn't really make sense though, because the issue of Semantics is also about communicating the idea between two people, and each person's mapping of a English sentence to a computation is a somewhat abstract idea. Anyways, either the semantics of the query doesn't reflect our qualitative definition of the metric, or querying the dataset is not a "closed-path", meaning one or more of the paths consists of wrong or inaccurate data. In which case, the solution is to be explicit about how a particular is computed, rather than WHAT we're desperately thinking we're getting at. Actually, it was when I first wrote two different queries to calculate the same metric, and having the numbers differ on an order of magnitude that I realized what we call confidence borders on quantified faith.