I remember a time as a teenager, pre-CNC, when I was pressing a machinist to assist me in engineering greater accuracy for my woodworking tools. I was contrasting the fine control of a vertical milling machine with my "bump and scoot" table saw fence, and I was convinced I could revolutionize woodworking if I could replicate that same level of control. (Today that accuracy is readily available. I use it all over my shop). But this machinist's comment has resonated with me for decades, "You're not working with aluminum here, it's wood!".
Of course, his point was wood can alter dimensions while you watch it. Wood can be dramatically subject to changes in humidity. If it takes on moisture it swells perpendicular to the grain direction. As the moisture is removed, the wood contracts. These changes are measured in 1/64, 1/32, even 1/8 inch increments.
Metal knows no such changes. The closest you are going to get to a "wood to metal dimensional change comparison" is if you are measuring massive corrosion layers on the surface of the metal, and that will be in the 10's to 100's of thousandths of inches, not 1/8".
There was no arguing his premise, as decades of woodworking have since confirmed. For all the effort that can go into ensuring ultra-precision accuracy in woodworking, wood "moves", baby! My simple understanding at the time was (and it persists to this day) if wood can demonstrate such dimensional fluctuation when contrasted with metal, and wood is the primary tone generator of an acoustic instrument, then tone (or quality of tone) will also fluctuate from (to a lesser degree) environmental condition to environmental condition, and from (to a greater degree) wood to wood.
This helps us understand why guitars built entirely by machine, in processes devoid of so called human error, can sound markedly different. If a batch of instruments are built entirely by machine using woods that are all from the same tree, or woods that are otherwise negligibly distinct, then those instruments may very well sound nearly identical. But when they differ, and boy can they differ...
Yes, it has "got to be the wood".