Not only is the learning curve for Adobe Photoshop steep, it is not likely the primary tool for cover creation. I do not know but I imagine Adobe Illustrator is used more often.
There are also page layout programs like Quark Express or Adobe InDesign (taking over from Aldus' Pagemaker) but their learning curves are steep too. I'm do catalog work with Quark and after many revisions it remains a very difficult yet powerful program.
Aside from the tools used, the issue is similar to telling a non-writer, "here's a copy of MS Word now go write a novel." There is a real skill and depth to graphic design.