I believe it. Obviously there are exceptions, when a whole function is dropped for example. And the biggest caveat is that "low performer" in the eyes of a company is does not equate to any kind of objective judgement about a person's intelligence or competency, it's heavily situation dependent.
That aside, it's common sense that the people laid off are skewed towards those that the company doesn't want, so people at the bottom of what the company defines as performance. Companies don't just arbitrarily dump those who are making great contribution to what the company considers important, whatever they may tell you