A layoff fundamentally changed how I perceive work

There are a few reasons for this, but the most concrete is that your behavior in this job has an impact on getting the next one. The author is correct that exemplary performance will not save you from being laid off, but when layoffs come your next job often comes from contacts that you built up from the current job, or jobs before. If people know you are a standout contributor then you will be hired quickly into desirable roles. If people think you are a hired gun who only does the bare minimum that next role will be harder to find.

On top of that, carrying around bitterness and cynicism is just bad for you. Pride in good work and pleasure in having an impact on customers and coworkers is good for you. Sometimes that means making dumb business decisions like sacrificing an evening to a company that doesn't care, but IMO that sort of thing is worth it now and then.

To be sure, don't give your heart away to a company (I did that exactly once, never again) because a company will never love you back. But your co-workers will.

This is completely false. I literally haven't seen someone do a reference check once in the last 10 years. Early 2010s it was more common but this practice is dead. Now every company is a new slate. In fact, I've seen people repeatedly rewarded for jumping ship and build there career on that. Companies have stopped investing in devs, so why should devs not reciprocate?

And there are so many startups. More than you can count. There are more new ones every day than you could ever have time to apply to. They don't all have time to talk to each other.

Not saying it's not good to have pride in your work, but within reason, and within a framework of fairness and quid pro quo. Don't let people exploit you any more than you exploit them. Employment is 100% transactional and the moment you forget that is the moment you get taken advantage of.