Pinning design options..

I've seen single, double and triple stacked washers, but rarely do I see no washer. Ivory being the exception is there a reason why razors aren't pinned without washers, like when pinning knives?

I've scoured the forums here and again, ivory aside, I have come across only one straight that was pinned with no washers...

There are actually quite a few w/out washers, Shumate comes to mind, many of theirs are done with no washers...

Many of the Case Family razors also, these are just a few come to mind at the moment..

I have an early 1900's Henckels that is washer less. The scales are not Ivory either

So, is it simply aesthetics? Or does the scale material dictate washers or none?

Trying to think here..

But I am pretty sure I have seen washerless on every scale material,,