Why are holds made of wood?

So it seems like the gyms have more and more bouldering walls made of wooden holds. Why is that?  I figured the plastic would help your hands get stronger and build calluses. Also I have seen home walls made of wooden walls also.
I know wooden hang boards have been around for forever but what is the benefit? 

They come smooth, people want smooth and natural, especially for training

Yeah, a lot of people like them because they're skin friendly. But if you mostly climb in the gym it can be a detriment to not rough up your skin to get it ready for the rock. 

They also can be good for training because you can't be as lazy with how you grab the holds. You have to really engage them. And more slippery holds probably promote use of better body position.

I climbed on a bird tonight that was all wood. I couldn’t keep my feet from slipping.
it felt kind of dangerous honestly like every 2 seconds I slipped off and was falling all over without warning. At least on plastic I know when I’m gonna break free.

I dunno maybe I’ll get used to them.

I just assumed you would want to tuffen up your hands for outdoors 

Sometimes rock is slick

K, so I guess what I’m talking about is a tension board

Cool stuff

Bobby S wrote:

K, so I guess what I’m talking about is a tension board

Cool stuff

generally i feel like i can climb almost 2x as many problems on a tension board in one session vs. a moon board bc a moon board shreds my hands up so much, although i do have soft little baby hands so ymmv

Makes you more precise and you're relying on your strength instead of the friction of a hold to keep you on. At least that's how I've looked at it

Nick Niebuhr wrote:

Makes you more precise and you're relying on your strength instead of the friction of a hold to keep you on. At least that's how I've looked at it

Absolutely.

Most rock I climb is more friendly on the skin than a fresh plastic hold. I sand plastic holds smooth sometimes.

Tension board is an excellent training tool, but the majority of gym climbing holds overall will always be made from plastic/resin, because it allows for a much greater variety, and more elaborate shapes, that can be achieved by pouring resin into molds, on a commercial scale, vs carving out of wood. 

So no worries, you will always have plastic to climb on. But Tension board is quite brutal at pointing out the sloppy footwork and lack of tension. If your feet are skating off, time to learn how to apply tension through your feet, and your climbing will benefit.

I’m not particularly concerned with toughening the skin by gym climbing. On the list of benefits of gym climbing, I would put it dead last, if it makes the list at all.

FWIW, Kilterboard, while made out of plastic, feels just as gentle/skin-friendly as wooden holds on Tension board, while Moonboard is definitely skin-shredding grippy plastic (unless you count the wooden hold set on moonboard, which I’m not strong to use, lol. But even their wood holds are more ribbed/grippy than tension board)

With a little more experience you will get it: Skin pain limits the duration of most workouts after you've been at it for awhile. Wooden holds are less painful and require more work to hold.

As some posters above have alluded to, you don’t want friction to do the work for you. 

Frank Stein wrote:

As some posters above have alluded to, you don’t want friction to do the work for you. 

Lol o yes I do!