OOOOooo... is that a rule to preserve the styling to ensure it goes down the runway according to the designer's vision? Or do they not want models to damage the samples?
It's both but mostly the first one, respect for the vision. Damage isn't usually a big worry. Most pieces (esp RTW) aren't fragile but also why chance it.
Different designers/creative directors (CDs) have different rules and freak out about different things. Some are way more neurotic. So to be safe and avoid any chance of issues, I tell my girls NEVER touch anything that you're not specifically told by the CD to touch. Even if you are told by the CD to touch it during your walk, ie like put your hand in a pocket or whatever, make sure to show the CD and the dresser what you think you've been told to do and confirm. "Like this? Is this OK how I'm doing it?"
Because if you're walking and you touch it and it falls or twists or shifts or wrinkles or bunches or whatever, you are going to get all the blame. If you think something feels off and you touch it to try to fix it and then it gets worse, you will get blamed. But if anything goes wrong and you didn't touch it, then it's on the CD and the dressers.
For a lot of the designers esp the older ones they can be super insane about respect for their vision, etc. You're a model not a designer. The designer sets the look and vision, it is your job to display it, not change it in any way because you, a "lowly" model, think it's wrong or off somehow. It's extremely disrespectful and presumptuous to think you know better than the designer. I've had girls pulled mid-show for doing it. Like in one instance my girl does her first look, touched it, and the designer freaked and nixed her 2nd and 3rd looks. The designer literally chose to NOT show those two looks instead of letting my (her words) "ridiculous, immature, stupid" model show them. (That designer is a name you would definitely know.) Also, that model never booked another show with that house.
And that's where it gets real for me, because when one of my models fucks up, it reflects badly on me.
I'm not saying I agree with all of it (although tbh I mostly do), I'm just explaining what has been screamed at me many times before.