People in humid climates and cold climates were regularly having their phones get denied warranty service because the water ingress stickers turned red due to condensation, without ever exposing their phone to water immersion. This was understandably upsetting for a lot of people who just wanted their phone to be fixed under warranty.

Thus, companies put in a big effort to seal their phones against dust and water, which ought to have dramatically reduced these service issues and led to a better customer experience overall!

There is waterproof specification levels. I haven't met one consumer product which doesn't let moisture in. I live in a hot country (not over 40ºC mind you)

If I not being precise, keeping your phone in your jeans deep tight pocket when you are sweating or raining will cause you problems. It might seem too many coincidences for you, but it is common enough that some of us avoid keeping the phone in the pocket.