Note that it's not just radios that have to consider performance at radio frequencies!
The frequencies of concern in EMI are not the fundamentals, but the harmonics, which are largely determined by edge rates. Something like a switching converter operating at 100kHz can easily radiate into the tens or hundreds of MHz, because of the edge rates involved. This is also a consideration with data lines, but switching converters are a particular concern, because the voltages and currents are higher, which means that the current and voltage rates of change (dI/dt and dV/dt) are correspondingly higher, so interactions with parasitic inductance and capacitance are more significant. Thus you see via stitching in basically anything with an MCU or a switching converter, because such things are always de facto RF boards--plus via stitching costs basically nothing, so it's cheap insurance even if it's not strictly necessary for a particular application.