Generally, with 20% down you are leveraged 5:1. So even if your home is just keeping pace with inflation of 3%, you actually experience 15% growth on your investment. To use the example in the article, if your investment doubled between 2009 and now, your $200k in a $1M home just became 1.2M. 6x growth beats out 3x growth in stocks in the same period.
Sure, you can be leveraged in other investments but (1) your interest won't be tax deductible, (2) your interest rates won't be nearly as low, and most importantly (3) you won't be able to borrow with no recourse (depends on the state law, but "no recourse" means your downside on a primary residence is limited to the equity in the home. If you default on the loan they can't come after your other assets.)
Does it mean renting is a bad idea? No. There are plenty of reasons it might make financial sense to rent. But articles like these should accurately discuss the financial upside of buying.