Does it really matter? Can someone else use your pen?

[Sumi]

We all heard it before. The argument that you should not let someone else write with your pen because it would change the writing characteristics.
Since first grade this it what our teacher would tell us explaining to keep your precious writing instrument as a personal item.
I have always subscribed to this line of thought without really questioning it but lately i do.
I can think of many reasons why i would not lend out my pen but to be honest I can not think of a reason why it would write differently when someone else has used it.
That is if they don’t abuse it of course.
If the user does not apply too much pressure and uses a fairly light hand i can’t see how anything could possibly change.
The nib should just spring back as it always does. Unless you have them write a mile worth of words no measurable amount of wear can take place.

What’s the big deal? I don’t see it really...