Companies do care about performance / output, and anyone who works in a group setting can see that there is often a clear difference in this metric for people, and for many people this difference is consistent (it's not a matter of having high days or low days, their highs are consistently high or above average).
In my current team of 8 engineers, 2 are clearly way above average in their overall performance and output. They pay attention to detail, they actually think through their designs, they care about code quality, they are diligent in code reviews (while others mostly just rubber stamp each other's shitty code) and hold each other accountable, they are useful sounding boards for design discussions while the others just nod along, and they are generally proactive with finding bugs and fixing them.
As a manager, I want more of these people on my team, except there is just no way to actually find this out by interviewing. All these people did similarly well in their interviews, and in fact one of the so-called 10x candidates did less well, because they are a bit more polite in nature, that causes them to sound non-committal at times.
The only way thing works is a direct testimonial from someone who has worked with them, but this is not scalable, and these days we are told we shouldn't rely on that anyway as it favors candidates with 'networks' and disfavors candidates from underrepresented minorities.
References rarely talk ill about a candidate, but when you ask a reference about a good candidate, they literally start gushing with praise, while for the average or mediocre ones they say generic things and are relatively muted in their praise.
Many industries work this way. In the legal industry, for example, interviews are mostly perfunctory / nominal, because they work through a chain of strong recommendations. Of course, the flip side of that is that it is extremely credentialist.
The Tech industry is the opposite. Most generally smart people can get in by doing a few hundred hours of Leetcode but you have no idea how they will actually be on their jobs.