That's ridiculous. You were just talking to 2-D thinkers, that's all. Sculpting does not *require* drawing skills - I'm a prime example of that. Sculpting is hard for those who aren't 3-D thinkers. For those of us whose minds work in the 3-D realm, it's far easier than 2-D work. The vast majority of art teachers (and art shop clerks) are PAINTERS, not 3-D thinkers, and they don't understand how to teach a 3-D thinker (this was my problem in all my art classes until I finally found a sculptor as a teacher when I was in my 40s - that's why I'm primarily a self-taught artist). People who don't think 3-D don't understand the way 3-D thinkers think, the way we see things, the way we relate to things - seriously. And they believe you have to draw before you can do anything else in art. They'll point to famous artists who were/are both painters and sculptors (Michelangelo, for instance), but he considered himself a sculptor and claimed he couldn't paint (despite the evidence of the Sistine Chapel ceiling). I'm the same way - I learned to draw after becoming a proficient sculptor and it is HARD HARD HARD for me to do 2-D work, but I can if I have to. Don't let a 2-D artist's limitations (which they don't even realize they have) make you the least bit hesitant about sculpting. Sculpting is in your hands and your heart and your mind and you'll be amazed at what you can create once you understand the materials you're working with.
Now that I'm done ranting (for now, LOL!), I will say it's always good to learn anatomy any way you can. However, learning it by DRAWING isn't necessarily going to help you with learning how to sculpt it. You'll need to study photographs done in excellent light to see how muscles move under skin (for instance). You'll need to pay attention to how the body moves - for instance, have you noticed that when someone is walking, the leg bearing weight makes that hip actually higher than the other one? It's pretty obvious in horses, but it's true in people too. If group of muscles bulge, the same ones on the other side will be shaped differently. I'm a horse artist, so I'll use horses as an illustration. Muscles bulge the most when they're contracted, so when a horse is LIFTING (not standing on) his left hind leg, for instance, his hip/rump muscles (and abdominals, etc.) will be bulging while the muscles on his right hind leg, the one he's standing on, will look flatter because they're engaged in supporting the body, not contracting to shorten and move forward that leg. The more effort being expended, the more bulge you'll see in the muscles. Muscles at rest are flatter and more relaxed looking than those being used to lift a limb. If you haven't studied anatomy, you may not have consciously noticed such things, but they're also true in humans. It's easiest for me to see muscle movement in dancers and body-builders. Most people don't have the muscular development or have too much body fat for the muscles to be defined the way I'm used to seeing them in horses, so I use upper level dressage riders (who are strong athletes and always have highly developed thigh muscles and lightly developed calves - which is a sign they're dressage riders rather than jumper riders or western riders - just a detail to be observed if you want to portray the sport properly) or dancers as reference.
There are 3-D anatomical models you can touch, move, light different ways to help you see anatomy. I'm not talking about those wooden doll things you can pose to get proportions. There are resin castings that are copies of Michelangelo's David's ear, eye, nose, mouth, etc. There are full-body anatomical models in resin. They're not all inexpensive, but they're useful. There are some models that have half the man's body with skin over his muscles, and half showing the muscles with no skin. You can get horse models like that too. That's the way a 3-D mind learns anatomy, that and studying the real subject you're going to sculpt, whether people, horses, wildlife, etc. (Suggestion - if you're going to sculpt wildlife, run your hands over some taxidermy models - good ones - rather than getting THAT friendly with a real cougar or whatever! That's what I did to sculpt a cougar - worked just fine.)
I see with my hands a lot. When I did my first portrait of a horse (rather than doing "imaginary" ones or ones based on reference photos), I was allowed to sculpt from life. The horse was tied up and I put the 3/4 finished bust on a tall tack box near him. I closed my eyes and ran my hands over that lovely stallion's head, then did the same to the 1/4 life-sized bust of him I was working on. The resulting bust is easily recognizable as him by those who know him even without his huge blaze (white marking on his face) that covers most of his face. For people to recognize him that way rather than just thinking he's "just" a Quarter Horse is remarkable and really amazing to me since it was only my second attempt at a realistic horse.
Don't let shop assistants deter you from sculpting. Get your hands in the clay (when using Super Sculpey, condition it first or your hands will get sore - it needs to be run through a pasta machine - rollers only, not cutters - several times to mix the oils in and soften the clay before you try to use it). Once you start working with the clay, your hands and innate knowledge will get you started on your first pieces. Then you'll see where you need to improve your knowledge and skill and the rest of it will be a joyful path of discovery. Let the 2-D people just roll around in their paints. We're creating art you can touch, feel and appreciate from all sides. Good luck with it!
Hmm. This looks like it could be a good blog post and I've neglected my blog lately. Thanks for the question! Off to post this on my blog! (www.abraxan.blogspot.com
, if you're interested)