I looked up the article. I don't see any reference to the $23,500 max? I think it would just be referring to the person earning 65k putting away around 10-12% and then the employer matching 3-4%?
Earlier in my career (12+ yrs ago) I worked on some 401k audits. The biggest one was a small publicly traded company with ~1500 employees in the Midwest. Medium cost of living area where it was fairly easy to for people to afford a house. There were people making 60k and maxing out their 401k and people making 150k that would opt out of the auto-enrollment and put nothing in.
We have 35 people in our office and pay above average for the area. We match 7.5%, $1 for $1, and still have some employees not putting in 7.5%