Via fencing is used to reduce electromagnetic interference in critial parts of a PCB. My question is, why do we not just cover any ground pour of the PCB with via fencing? Are there disadvantages that would come with that?
Because a via fence also requires continuity across a large area of the board on at least the top and ground plain, it's difficult to route signals through a via fence, so its probably not wise to cover the entire board with it. Cost is usually not an issue unless dealing in large quantities.
Via fences will provide capacitance to ground, so that would be the main advantage\disadvantage.