There's great flexibility in drawing a picture: endless subjects to draw, different styles to try, many tools to choose from, and canvas -- anything can be your canvas. Even so, many people out there think that they can't draw. They think those who can draw, even further, who can draw things with elegance and meanings, must be born with special "talents".
Not true.
Yes, there are definitely people born talented in drawing -- they grasp the gists and quickly grow, but most master it through long-term practice. No one starts out drawing a masterpiece. But, as long as you start somewhere and keep going, there's a good chance that you'll establish your own style, and become a master one day.
I think when some people are saying "I can't draw", what they really mean is "I'm just not into drawing, and not interested in learning about it. It's good enough to see others draw". So, they would feel uncomfortable if someone urges them to learning it. Although giving drawing a try once in a while might work for them.