Dallas tap water carries a fair amount of calcium and magnesium. Heat that water every day for years, and those minerals drop out and settle at the bottom of the tank. On a gas unit, that layer of sediment insulates the water from the burner, so the steel overheats and the tank starts to pop and rumble. On an electric unit, the lower element ends up buried in scale and burns out early. Hard water is a big reason so many local units fail before their 10th birthday. Flushing the tank once a year keeps that layer thin and the unit working the way it should.
A lot of North Texas homes have water heaters in the attic, where summer temperatures can climb past 130 degrees. That heat wears on valves, wiring and plastic parts. A leak up there is also more serious than one in a garage. By the time water stains show up on the ceiling, the drywall and insulation are often soaked, and mold growth can follow within a couple of days. Garage units have their own concerns. Gas models need to sit up off the floor to keep the burner away from fuel vapors, and many older installs don't meet that rule.