Many compact cameras do use similar ideas, just under different names. When you set a camera to record at a lower resolution, it often downsamples the full sensor data, and some cameras also use extra sensor resolution for digital zoom features marketed as “smart zoom,” “fine zoom,” or similar.

A closer match to PureView is pixel binning: combining neighboring pixels before readout. This can improve low-light performance because the combined signal is stronger before read noise is applied. That requires extra sensor design/circuitry and enough excess pixel count to make the trade worthwhile, so it’s less common in typical consumer compacts.

Some compact-camera systems have used related approaches. Fuji’s EXR cameras, for example, combined same-color pixel pairs for lower-noise images and could also use pixel pairing to increase dynamic range.

So the short answer is: it’s not that cameras never do it; many already do some form of oversampling/downsampling, and a smaller number use true binning-like methods. The limits are mostly technical and design tradeoffs rather than simple commercial neglect.