That's right. However, being able to do everything is not the goal, is it now? Nah, what I have personally learned in video games is that you can teach yourself anything you want. The only limitation is the amount of subjects you can handle in your study window... And then of course there's the dreaded expiration date of organic meatbags humans.
Is not having scripted a comic before what you define as your limitation? Because that's not necessarily a limitation.
If you want to make comics, then just do it. You don't have to make canon comics right off the bat if you don't feel confident enough doing so. But get started practicing, share, get feedback and improve.
If we really have to talk about limiting factors, it's really all a matter of how much spare time you want and/or can "sacrifice" in order to teach yourself this new thing.
oh... And here's a TED talk... Because I can.
To all other people reading this comment, of course I made all of this sound easier than it is, but can you blame me for trying to convince Matthew to do comics?