TJX Cos. shouldn’t discount the lessons learned from the demise of American department stores. Chief among them: Building too many brick-and-mortar stores can be a dangerous way to stoke growth.

On Wednesday, the parent company of TJ Maxx, Home Goods, and Marshalls talked about its plan to grow its off-price store count by 50 percent over time, adding 1,800 stores to its current base of 3,800 stores around the world. About 1,300 of them would be in North America. CEO Ernie L. Hermann sounded downright giddy when he told Wall Street analysts he “didn’t close a single store last year” despite the retail Armageddon unfolding all around the seller of discount goods.

It seems out of touch to be so flippant about opening stores at a time when Macy’s Inc., Sears Holdings Corp., and most of America’s retailers are going in the complete opposite direction. They’re either slowing new store growth (like Wal-Mart Stores Inc.), nearly halting it altogether (like The Home Depot Inc.) or closing locations that have been hit the hardest…