Primer compositions got ironed out pretty well by the mid-20th century. There were chlorate primers, which lasted essentially forever, were cheap, easy to manufacture, inexpensive, insensitive to temperature, and left corrosive residue. There were several types of non-corrosive primers, eventually settling down to lead styphnate and various additives. The styphnate primers were temperature-sensitive and harder to handle during manufacturing, but became the standard for everything other than some of the old Communist Bloc.
HOWEVER, since the "lead primers are poisonous!" fandango of the early 1990s, manufacturers have been trying various lead-free priming compounds. Some of this is driven by military and police contracts, which favor or specify lead-free primers. Many of these primers DO have a shelf life, and go erratic or simply go inert when they expire.
The primer sits between the powder charge and the firing pin. A certain amount of kinetic energy is available from the pin; this is a fixed parameter. The powder is designed to be ignited by a primer with a certain amount of power, or "brisance." You have some wiggle room with the powder, and you could probably make more or less easily ignited powder to match a nonstandard primer, but for most purposes, any new type of priming compound needs to be pretty much a drop-in for the existing compounds.
Whether Federal is using some new short-lived primers, or they're just playing "Product Liability CYA", I don't know. But I doubt they're scaremongering sales, since they can't keep up with the demand for primers right now.
