Anecdotally, it sure seems that the job-hopping that is increasingly common is a factor.
I have a lot of friends that took the cash from their 401k when switching jobs. They only had 1-2 years of contributions in there, and most of them "needed" it for relocation or other life expenses surrounding a job change.
The article notes that people "don’t see the balance as being big enough to matter." Which also rings true with my cohort of 30 something professional friends.