I've been guilty of that. I hacked off the brake guides on an old Vulcan. Granted, someone had already brazed on track dropouts, but I certainly regret it, as it made a better singlespeed than fixed. Aside from me, maybe one out of ten-fifteen conversions I see have that happened to them.
In any case, how many of those "precious" Voyagers were lying in the back of the local thriftstore gathering dust before some kid got inspired to pick it up and convert it?
Poor, poor steel purist. Steel has been dropped in favor of carbon, the kids picking up the vintage steel are either retrofitting them with STI's, or worse yet, having their derailleur hangers lopped off for a "cleaner" look.
Except... Regular Track Frames have become so cheap and readily available, that the last one is a very rare occurrence.