Back when two-layer boards were the norm, one of the main reasons for using a hatched pour was to help balance copper density between each PCB layer and reduce the risk of warping during fabrication. A hatched pour behaves mechanically more like a set of traces than a continuous copper plane, which made it less prone to stress compared to a solid fill when paired with routing on the opposite side. In current HDI manufacturing, you rarely see hatched planes used for this purpose, but the same ...
