I'm not at this point yet, but reading this makes me wonder why any employer would ever prefer younger employees with nothing tying them down, for any reasons other than the fact that we cost less. Sure, you'll save money on salary, but odds are that we're going to move on within a year or two if you're not a top-paying company. Even then, there's no guarantee.
Meanwhile, someone who has dependents and a mortgage has more to lose and less leverage.