Just took a good look over 2-and-something-years-old ZenFone 2. I've only noticed some very light scratches upon a careful inspection, only when looking at the display surface at angle where it had reflected daylight. Dust specks are way more noticeable.
I don't use any protectors, I put the phone in my packet together with my keys, my cat tries to chew on it every time he sees it lying on the bed (I don't know why), and otherwise handle it quite recklessly.
The only way I really got cracks is when phone fell out of my hands, face-down on a gravel. Happened on a second month after the purchase, had to replace the display (but still decided I don't want a protector film)
Now, reading about the scratches I wonder how bad it is with iPhone X.