A lot of people I saw being let go at my company weren't very good at their jobs - either because they were not capable or because they were not willing to do a lot of work - and leadership took the opportunity, in their eyes, to get rid of them. I'm not saying it was the biggest factor, but I wouldn't say it was "by far the smallest" based on my observations.

Agreed. I saw lots of really really questionable people not get laid off. It seemed to depend much more on business unit than job performance. Though once you are already in a business unit that is being cut, maybe it is performance related, not sure.

This exactly I want to discuss this issue: Neopotism