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.