It doesn't make much sense to me that hitting the limits would be so rare. Why have the limits in the first place if that's the case? If they didn't make a difference, then they'd just be bad propaganda for the insurer.

This random web page I looked up indicates that about 20,000 people are impacted by lifetime limits:

http://www.pwc.com/us/en/healthcare/publications/lifetime-li...

This is not a huge number, but it's not completely irrelevant either. The pool it draws from will exclude the elderly, the study only looks at the people with employer-provided health insurance, and the 20,000 is from the 55% of those who have lifetime limits.

The Census Bureau says that about 170 million people have employer-provided health insurance: http://www.census.gov/prod/2011pubs/p60-239.pdf

So we get about 93.5 million with employer-provided insurance with lifetime caps, and that in turn gives about a 0.02% chance of hitting a cap.

Whether that qualifies as "exceedingly rare", I'm not sure.

In any case, "$100,000 hospital bill" is probably a decent substitute for most people, although the odds of being bankrupted by that are probably considerably lower among the HN readership, at least.