I don't know whether you, or anyone, should be an editor. That is a personal choice as well as a professional one. But I cannot say you shouldn't. But consider this: when someone begins training to become a doctor, the first-year medical student cannot be expected to treat people. Neither can the first law student. Why should you, after several assignments, be ready to edit for Knopf?
Years ago, becoming an editor was a different process. At least for most editors I know. We went to work for a major publisher (or even a small independent press) as an editorial assistant, and basically learned "on the job." Every project taught you something new. I also found that working at several different places offered the opportunity to work under people who could give me something different.
The point at which you feel "I am really an editor" happens when somebody has given you editorial work, and they are very happy with it. When I first graduated college, and someone gave me something to edit, I felt totally at sea, and I had studied linguistics and gone to schools where they taught a great deal of grammar. I was frozen. I didn’t know what to do with what I was holding in my hands. I needed to go through at least some apprenticeship; at that point, I didn't even know how to mark up a manuscript!
These certificate programs are a wonderful thing. Not just because everyone cannot come to New York and work for a publisher, but because very few people in New York can do that any more. It's a different world. This is the apprenticeship. And at this moment, you have unrealistic expectations. There are a few people in the course who can edit right now. But they have been working at it for some years (we’ll keep that secret). But I’m glad they are conscientious enough to want to make their work even better. That’s dedication.
Don’t think about whether you should be an editor. Think about learning grammar. You see, learning grammar can do amazing things for you even if you become a lawyer, a community organizer, a teacher, or even an architect. That’s one of the great things about this program. It is actually useful to people in all occupations.
But what I love most about being an editor is that I am always learning.