That's what I discovered when I first started learning the program. Since then I've made it a point to demystify the coloring process for students who have little to no experience with it. Take this demonstration for example. It was created last year while teaching at California State University Northridge.
From the initial digitized concept sketch drawn in black line and embellished with blue pencil I punched the overlapping shadows with a transparent gray.
Next I rendered the image in layers of transparent grays to establish tonal relationships.
While working in transparent layers I tinted the composition with color.
In no time at all I made pretty good progress. I had the option to continue but decided to leave it at this state of development. I was able to communicate I simple method of digital illustration to the class resulting in something that I could share on my blog a year and half later.