You can't just say "80% is wasted" when it's just wood that is used for other purposes than timber. Until we can convince Mother Nature to grow trees which are

You can't just say "80% is wasted" when it's just wood that is used for other purposes than timber. Until we can convince Mother Nature to grow trees which are perfectly straight and preferably already square, the process of converting a cylindrical log to a square beam will inherently have some cutoffs. The linked article in turn links to a research paper at https://www.woodresearch.sk/wr/201202/12.pdf https://www.woodresearch.sk/wr/201202/12.pdf, and while that paper does support that only ~20% of a tree gets sawn into long pieces of (construction) lumber, it absolutely does not support that the remaining 80% is waste. For example, ~37+9= 46% goes to the production of chip and particle boards, a decent amount becomes firewood, the paper industry takes some "waste" wood as input for cellulose production, sawdust has a variety of purposes and even the leaves and stumps can simply be composted.