Well, I believe this is not entirely true. You might capture the stuff if you fiddled with STDOUT and STDERR enough, but it would not be nice. And it's totally unnecessary. So I think the precise answer is "You could, but it would not be pretty so you should not. Use the tools that were designed to do that!"
Jenda Enoch was right!
Enjoy the last years of Rome.
But that wouldn't, specifically, be using the system function. It would be using "the system function plus a lot of other stuff". Otherwise known as backticks or qx//, which had already been specifically rejected.
Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
"Science is about questioning the status quo. Questioning authority".
In the absence of evidence, opinion is indistinguishable from prejudice.