Washer under stem on #25...why?

Moved on to next watch in pile; another #25. Cleaned up great and sitting on bench. Thanks to Dorsey for sharing service procedure; I'd missed lubricating the escapement pins.

On disassembly, found a small round washer under the crown. It sits in the space between the case and the crown head.

Why is this in place on this watch? I assume that someone replaced the crown and put this under as a spacer? My inclination is to remove it; it's making it hard to pull out the crown to set.

I've got a weird Korean #106 next. The square "case" is 2 part; a gold-colored outer and a chrome inner that pressed in. Crystal and seal was held between the two halves. Has a dime-sized case back that allows you to pull the stem, then the movement removes from the front. Since the case splits, no need for a crystal lift... good thing b/c I don't own one yet.