Many people inadvertently bang their watches against door jambs or other objects and sometimes scratch or damage the crystal. This happens while the watch is secured to their wrist. Other people never do that and never get a scratch. Being secured to their wrist isn't the reason the watch isn't damaged.
I'd posit that most have relatively inexpensive watches as daily drivers and if they get scratched or the crystal is broken, they just get another watch. Not a big deal. A lot of Apple Watch owners or any smartwatch owners may have never had a watch this expensive and just buying another one isn't an option. This is why some people by Apple Care for the watches.
With 'dumb' daily driver watches, most people look at them for just the time or occasionally the date. If you spend a lot of time looking at a smartwatch for texts, weather, notifications, and other data besides the time and date, a scratch or scratches might be a lot more annoying. I don't know about anybody else's smart watch, but I'm glad Apple has taken some steps to reinforce the crystal.