The use of ANY blocks, wood, plastic or otherwise, is just a matter of choice. It's also a matter of how well you treat your coaches dynamics in terms of how far you plan on lifting it, in one corner etc. because you don't feel like using leveling blocks. Again, a matter of choice. I've made and have been using wood blocks for decades. And, the way I make them, they LAST for decades. Nominal wood, i.e. 2"x 8" and 2" x 10" etc, will crack, it's a given, just when, it's a matter of time.
But, I sandwich my nominal wood in between 1 1/8" decking plywood that is tongue and groove stuff. It's seriously strong stuff. Yeah, wood is a bit heavy but, SO IS THE COACH! I have the yellow leggo blocks too from C/W and, some ramps I've made along with some 11"x 11" x 6" jack blocks.
And we've needed them countless times. We camp in N/F campgrounds, State campgrounds and private campgrounds, all of which have had countless spots that were unlevel. And all this crap about "Well, if it's un level, just move to another spot". Yeah sure you will. With the amount of folks camping/living/staying/retired etc. out there filling up all the campgrounds, just "moving to another site" AIN'T GONNA HAPPEN!
So, we've made do, countless times with our small lumber yard we carry. Again, it's a matter of choice. Sure, if the sites level within reason, as I can tell when I approach it, then there's no blocks/ramps needed and, I drive up and, set the brake and hit the HWH Power button twice which, auto bleeds the bags and, set's in motion, the auto leveling system. DONE!