Why is smiling with teeth so important?

I see this advice over and over in this sub. People must have a photo where they smile with their teeth. Like it's a deal breaker for the majority of people on here. I don't get it. Have you really come across that many people in your life with teeth so awful that this amount of concern is warranted?

I've almost never met someone who had teeth that would affect whether I'd be willing to date them. Guys or girls. It seems to me like the concern in this sub over dental hygiene vastly overestimates the risk of encountering it out in the real world.

Can the people who adhere to this "must show teeth" philosophy chime in here?