Bull. In small companies, I would agree that those that deserve to be laid off, do indeed get laid off. I watched that when working for a 250 employee company. In three years we shrunk from 250 down to 36 employees. In the early rounds of layoffs, all the unprofessional, lazy pricks got let go.... Ultimately a lot of good people got let go too in the later rounds.
Fast forward several years... I'm working for a 20,000 employee company... Four years of layoffs, and I get selected early in 2010 to go. The irony is, I made "The President's Club" that year for over-achieving my targets... and still I was just a number and let go. I made that award 2 out of the 4 years I was there... which in my position, was rare in the company. At the end of the day they had too many redundant resources, and they kept the other guy that was working some pretty important internal projects and was assigned to our largest customer all along. Meh.
Fast forward again... to December of 2010... I'm hired by a near 400,000 employee company - paying me more, and the HUGE irony is I'm now competing directly against my former employer in some accounts, and I'm going to stomp all over them with my success.
So... In small companies, the first round of layoffs take out the shit people, but in larger companies you are indeed just a number. Hard work and success doesn't protect you though I do think it delays the inevitable.