I've been through numerous rounds of layoffs, both of entire teams and of select individuals or roles, and it has never had a net positive effect on culture.
Large-scale layoffs very rarely (i.e. never) simply cut people that are "bad at [their jobs]."
It seems to depend on the company, but based on my observations the people who are first to go seem to correlate strongly with people, who management does not like. The remaining layoffs are a weird function of people, who know what they are doing and can't ingratiate themselves.
In my personal experience the first to go are the non management highest paid employees, the degree of competence doesn't matter. The really good ones go before the layoffs. The next layer of skilled employees leaves between the first and the second wave of layoffs. Eventually you get a company of drones with some management on top of them. Possibly a lot of management because sometimes they contract the same very people they laid out because they need the expertise but they want to transform capex to opex.
Totally disagree with both sentences. As I posted elsewhere, I've seen layoffs in a place I've worked as a way to finally get rid of subpar performers.
I've also seen cases (and this appears more relevant in ARM's case) where the company just hired way too fast. It wasn't that people who were laid off were necessarily bad, but there were just way too many people for the amount of work, and so in absence of clear purpose a lot of people would have tons of "make work" meetings that were really there just so they didn't feel totally useless.
I'm certainly not saying all layoffs are like this, but I do take issue with the idea that layoffs never have a net positive effect on culture.
No offense, but I think you are looking at "culture" through a pretty narrow lens (or just not talking about "culture" at all)...
Regardless of if you are "[hiring] way too fast" or "finally [getting] rid of subpar performers," layoffs are still, by definition, firing a bunch of people's coworkers. Simple work efficiency, which is what you'd theoretically be improving in both of your examples, has relatively little to do with company culture, so your examples aren't very compelling evidence.
Large-scale layoffs very rarely (i.e. never) simply cut people that are "bad at [their jobs]."