Gonna try to make this rant short.
The main point I want to make is that if you can't do it on paper, you can't do it on the computer. But i don't think that one medium is superior over the other. they both have several pros and cons. Traditional art (generally) takes less time, at least for me. there's more room for error, but mistakes are harder to remove or cover up, and your colors are more limited. Digital art lets you explore more manipulation and editing, and thank heavens for ctrl+Z right? but I think the biggest con for digital art is you learn very little.
I'm trying to find a balance between the two. I know that my digital pictures are always better after I make a traditional one. I've learned so much from watercolors alone, and I would be open to trying more traditional mediums to learn even more!
I guess my advice to aspiring digital artists is just to practice practice practice on paper using different styles and mediums, and your knowledge will transfer to you digital art as well, only you're much less limited.