If you're making $36k/year of mortgage payments towards a $600k mortgage (the article refers to a $750k home and an 80% mortgage) then you're not just paying interest; you're also making a significant dent in the principal amount. You don't need to put $33k/year into a retirement savings account if you're already buying $20k/year worth of house. (Whether the house is a better or worse investment than the stock market is an open question -- but the fact remains that there's no need for this couple to save over $50k/year towards their retirement, especially while they have young children.)
Similarly, it's misleading to count both student loan payments and the kids' college fund -- if they got student loans, their kids can too.
EDIT: Ok, I'm not familiar with the US housing market and mis-estimated where mortage rates were. They're paying off $10k/year of mortgage principal, not $20k/year.