It's more sadder than that
It's another effect of deforestation. Up until about 50 years ago, the 2x4 that were used to build houses came from trees that on average were about 60, 70 even 100 years old.
We ran out of those trees about 30-40 years ago.
Now most of the trees that are harvested for lumber are fast growing weaker trees that take about 10 - 20 years to grow .... and they don't even grow that big any way ... so the way they deal with smaller trees is to just harvest more of them.
Younger weaker trees will bend and twist more, break easier, not as strong and more suseptible to bugs bacteria and mold, because the wood is not as dense or hard.