If you've been using computers for long, you should already know VM thrashing can murder a system, to the point of making it unresponsive and needing a reboot. So this is an assumption you have backed by direct experience. And of course, probing it won't tell you anything.
But do you have enough information about how Redis accesses memory under the benchmark in question, combined with the OS page replacement strategy, combined with the characteristics of SSDs, to know the results beforehand? You can guess, for sure; but do you know?
If we all follow your approach, we'll never be surprised unless we get stuck; and if we know what we think we know as well as you seem to think we know it, we shouldn't get stuck in the first place. We should have assumed that we would have gotten stuck, and avoided it.
The article has relatively low value in terms of information content, but the mindset is to be commended. It should have given the author better intuitions about the 3 factors mentioned above. Modern, non-budget systems very seldom thrash; there's a younger generation coming along who've never experienced systems frozen in that way.