Only one of the municipalities -- Great Barrington -- is west of Lowell.
The article notes that, "Some of the winning communities -- such as Somerville, Charlestown, and Jamaica Plain -- are especially attractive to young professionals, particularly since home prices in these spots are more within reach (though still well over the state median)."
Of course, that all depends whose reach you're talking about. The median values in Somerville, Charlestown, and JP are, respectively: $445,000, $620,000, and $500,500. Especially with the way loan information verification and minimum required down payments have changed in the last several years, I have no clue how a young professional is going to plunk down a payment, and then afford to keep up with, notes that large. Absent a rich (and generous!) family member or some great investment skill/luck, that's hard for a lot of young people to do.
Assume a young professional single person or couple is employed or going to school in Boston or its immediate environs. Maybe they're set in what they're doing, or maybe they want to keep options open, but they realize that most of the likely options are in or near the Unofficial Capital of New England, and want to buy a place and stay within reasonable commuting ease/distance. With Brockton excepted (equidistant from Boston and Providence, both less than 30m), the other Gateway Cities (if we're using MASSInc's original list of 11), just aren't going to let you do that.
New Bedford and Fall River, at twice Lowell's distance from Boston, work for commutes to Providence but not up to the Hub of the World (I'm sure some people do it, but most would not. Worcester, Haverhill, and Fitchburg all have mass transit options, but if you needed to use a car sometimes, would cause you WAY more headaches over the course of a commuting year than Rte 3-128-93 would (not that it's easy to do except in off-peak hours, but still...)
Of course, Holyoke, Pittsfield, and Springfield aren't even in this equation.
For people looking to buy, but priced out of Cambridge-Somerville-JP-Charlestown and still looking to commute to Boston, or at least keep the option alive, you'd be down to just Lowell and Brockton as far as the original 11 Gateway Cities go. Oh, and Lawrence.
Without even getting into a which-of-these-cities-offers-the-most for people hypothetical scenario with a predictable outcome, or explaining why I would RATHER live in Lowell than in the trendier yuppie-burgs, I would just point out the obvious but sometimes-underappreciated Lowell's geography is an important factor in its appeal.