Hidden Character Sheets

I've noticed that most people do this. Not just here on GP, but everywhere. Why? Because it adds another level of mystery to the game? Is it some old school/ new school way of playing? Should I be hiding mine? Should I ask the GM?

They're hidden by default. Most people just don't bother or forget to change it

Unless instructed otherwise, I always share my character sheet. But that's me.
Not just about character sheets but about anything related to the game, really, this course of action has all the upsides and none of the downsides.

Wise words...