Image stacking is extremely common in low-light photography, especially astrophotography (where it is essentially the only way to get the 30min+ long exposures needed to image some deep-space objects). This need is somewhat mitigated by a sky tracker, which moves your camera together with the sky, but these are expensive and will slowly drift, making it still require multiple exposures (though you can get to several minutes before you get trailing, while without one you can only really get to a few seconds).

Basically, it's a pretty common technique for increasing SNR, it's a very different kind of "doing things in software" than, say, an iPhone's fake bokeh. It's no surprise that phones are starting to use it.