Sorry guys, I can't help agreeing with 'Graviman's' analogy with "how long is a piece of string?" and that 'slowrotor's' original post is simply a statement and not a question. Main- and tail-rotor blade erosion falls into the category of fair-wear-and-tear. However, as we all know, this can be exacerbated by local conditions - particularly dry sandy areas.
Take good care of your blades (wash daily if necessary) and they'll give good service. In my experience, blade tape, both polyurethane and metal, can be helpful but very often the effort outweighs the advantages. DO NOT attempt to counter erosion by local paint touch-up.