I came from a background in Photography and 3D before I got into painting and drawing. I definitely see things in terms of values and not lines...and really, even more than values, "planes"....weird that I don't particularly like sculpting, but there you go.
For some reason, I internalized the "You must learn the fundamentals!" argument, and I put both photography and 3D away in favor of drawing, and then basically colouring, comic book style, when I was in the first 2 years of art school. The teacher that I looked up to came from a comics background, and I really, really tried to do the work I was "supposed" to do.
Holy crap, I sucked. I sucked so badly that a guy at Arena Net I showed my work to spent 10 minutes trying to figure out how to tell me to give up and find another career. I sucked so badly that teacher I admired told me to break into comics WRITING...yeah, my art teacher told me to be a writer.
...and then, one day, for some reason, I tried painting in Photoshop again. It had been years since I had worked without making lines primary, and OMG, it felt so good!...then I used some photo textures I'd taken in Cambodia, and that felt even BETTER!...then I figured out that I could import 3D models into Photoshop, and I was in HEAVEN.
I didn't stop drawing. Drawing is important...but I didn't lead with my weakest toolset either.
Play to your strengths. If someone tells you that you are good at something, don't discount it as meaningless because you are good at it, and you see so much out there to learn. Work outward from your strong points. Like I said, I didn't stop drawing....I draw almost every day, and my drawing has improved to a point where it's not one of my weakest skills anymore...but if I'd waited to try to find work until my drawing was up to par, I'd be 2 years behind where I am today.
"I'm bad an anatomy!" Ok. Sure. But you want to work in cartoons. Have you LOOKED at "Adventure Time" lately? You don't need anatomy for that stuff. Learn it on the side, keep on trucking!
"I've never figured out perspective!" A'ight. You don't need drafting levels of perspective to draw trees....or do what most comic book pros do these days, and trace over Sketchup models.
"I don't know <xx> tool or medium." There are dozens I don't know either! I do my illustrations in the ones I *do* know, and then I go play with Unreal Engine, or Paintstorm, or Watercolor, or whatever in my spare time.
Moebius once said that every illustration you do should be 90% things you are strong at, and 10% experimentation. If you experiment fails, a 90% grade is still more than passing, and over time, that 10% will add to your tool box in new ways that keep you growing as an artist.
Some of the best movies in the world are that way because of the limitations, not in spite of them. The Star Wars prequels kinda wet the bed because there were no limitations. You can create successful work with a very limited toolset - in fact, it will probably be more successful, because it will be filtered through a set of requirements that are unique to you. The trick is finding what sort of work lends itself to what you know best - but that's a question that's worth putting to yourself!
Thanks for reading! Now go out there and make something :)