Nobody's perfect! I like the overall point of view, the pendulum has swung too hard the other direction in my area. Stampeding customers into craning out 8+ trees is super common. Neighborhoods get leafleted, "We'll have our crane removing some trees for your neighbor, would you like us to look at your trees?". I've been present at a customer's request while a locally well-known tree/crane service owner did a site visit. Started out pleasant enough but when he started suggesting that several other trees were a threat besides the one obvious hazard, and then talked about what a great deal they'd get taking out 4 or 5 trees versus just one I pushed back and things got weird. At the end of it he had the nerve to try and hire me to ride his crane ball ;-) Nope nope nope. I've talked several of my customers off the ledge, one had two tree services condemn all their white pines. On assessment I found one with issues but no targets, the rest was fabricated BS including "Climate change is killing your trees, you should take them down ASAP". Another told them a specific fungi was killing all their pines, absolutely not true. I kid you not.
This has nothing to do with the biology of retained deadwood but the article in question spoke my mind about exploitative practices in the industry, and deadwood is part of it. As mentioned somewhere above, deadwooding is essentially aesthetic landscape maintenance and obvious hazard mitigation over property and people targets. The trees often in question will outlive two generations of property owners. The hazard issues are more typically related to codominant structures, rot processes from previous storm damage, or mistreatment of the root zone and/or volcano mulching. I've seen many examples where rot (fungal intrusion) entered the heart of a tree through a collar where deadwood was in place for a long time. In my area typical for Quercus velutina and red oak family species in general. I think the scientific deadwood discussion needs to go deeper into specific tree species and regions. Quercus alba in the northeast doesn't follow Q. velutina rules, I'm sure many of you have seen hulking old white oaks full of hollows and empty "collar sockets", tree's good for another hundred plus years.
-AJ