At the time, the Mossberg 100ATR and the Remington 710 were the only base-model rifles out there. The ATR was a much better rifle than the 710 or the derivative 770 (did Remington really think that changing the dress and lipstick would make the pig more interesting?). The ATR's market success led to the dressed up 4x4 or Trophy Hunter, which are as good a rifle as standard 700's or Savage 111's and brought serious competition for mid-grade rifles. That and the MVP short action more-or-less forced Ruger, Savage, and Marlin to get back into the budget rifle race. The ATR is a rifle that can be upgraded like a Stevens 200 by the end user but also is an action that can be made fancier at the factory.
Were it not for the ATR's success, there would be no American, Axis, Stevens 200, or X7 (or the 4x4 or short action MVP). Those companies had to compete with Mossberg as they were losing market share in a financial move not that different from Savage in the 1990's.