I wonder how much this has to do with decreased building porosity. Used to be if you got water in some places it would just evaporate into the airflow. Anywhere there is no airflow, the water will persist.
Right. Modern construction standards, aiming to reduce energy usage, make it much easier to get serious water damage, and so necessitate spending more effort towards waterproofing.
Here's a good video illustrating what you're talking about: https://youtu.be/KBMMDY3LFAA?t=204 . If you had a leaky window like that with a house built today, you'd get mold and rot in no time.
