>>149560349All you need to do is look at line art to be proven wrong. I do agree that colorist should be credited more than they are - it tends to often be PENCILER/INKER and never "P/I + colorist" when people are talking about credits on covers, particularly variant covers, or interior work.
That said, people who do it all, who often tend to get credited as "art by so-and-so" also don't get enough credit for doing finished line art as well as digital color.