It is not that rare for critical employees to get grants as part of the layoff execution in a pre-emotive action, and now that I’m older I will note that I’ve been on the planning side of layoffs and this is fairly commonplace.
These companies could take a more twitter like "print out your code" or global stack ranking to lay people off but i don't think it dodge the problem people describe. The "A Player" could still be mad that all their coworkers got fired and/or the "pointless project" they enjoyed working on got axed and still leave. You just get the add cost, drama, and blow-back (see twitter) that a performance based firing would entail and probably open yourself up to lawsuits (IANAL) if you don't have an adequate paper trail for those performance based filings.
When I was younger I was shocked to learn that during an LR companies would “over” cut in order to fund retention for critical people. You’re laying off 7%? This is a good time to free up some additional opex, so just add a few heads above target in order to free opex to comp important people. You won’t get that 7% back but overage you do, usually.