There just may not be that many period bands that can travel to the whole spectrum of events. Truth be told, there's not much money in music, and the narrower you make your audience, the less there is. Also, musicians tend to see the music first and the history second. For instance, it's traditional to start a piano recital with a Bach number, even though he never wrote for a modern piano. While there are chamber orchestras that specialize in baroque sound, that's not going to keep the local Philharmonic from playing Handel. (I like to play 18th century murder ballads on an electric guitar too, but that's just pushing it )
Pine River Boys, Co I, 7th Wisconsin
"We're... Christians, what read the Bible and foller what it says about lovin' your enemies and carin' for them what despitefully use you -- that is, after you've downed 'em good and hard."
-Si Klegg and His Pard Shorty