I was very unclear in my original post, and so there is confusion by one or two people about what I am proposing. I'm not making any claims about when it makes sense to actually take SS. (Actuarily, SSA is designed so that for the average person, it doesn't matter. For the types who frequent these groups, who are likely to live longer than the average American, it should be 70. But again, my argument has nothing to do with that.)
Instead, I'm making a claim about what you should put into a sophisticated retirement calculator like cfiresim or firecalc. I argue that those calculators are about telling you a worst case scenario, and whether your nest egg would survive it. If that is what you are using it for (and I think most people are), then plugging 62 is more sensible than plugging in 70, even if in the vast majority of cases you would intend to take SS at 70.
This is, in other words, about what age you should RETIRE and/or what your nest egg should be before you do so--not about when you should actually take SS.