I think that is up for debate. Many, including me, contend constant banging by surges and spikes does result in cumulative effects on some of the devices, increasing their rate of aging. I had it explained to me once as being similar to loud music and jet engine noise on our ears. Eventually, the effects will catch up to us and hearing loss will result.
The facts are, surges and spikes are regular occurrences, even with modern, stable grids. But the vast majority are relatively small so I agree, with a quality design, quality parts, and relatively small anomalies, the surge and spike protector will work fine and last a long time - a lot longer than 2 years. But NOT indefinitely nor capable of enduring infinite hits, even if minor.
But here's the problem. No one (unless a tech/scientist in a proper lab environment) knows how many surges and spikes are hitting our electronics, day in and day out, or how severe those surges and spike may be. So there is no way for us "normal" people to realize the effects they are having on surge and spike protectors. So IMO, that 2 year recommendation is being conservatively safe. Too conservative? Maybe. I would say if you go with a quality Tripp-Lite or Panamax or similar protector, it will last many years under normal use.
Of course, if Mother Nature get mad and targets you directly, nothing will protect you, except a quality backup plan.