Marketing is neither good nor evil.
Design really can be anything.
I do different things. I'm a designer. I'm a painter.
Marketing is a necessary part of the creative process.
Marketing is not inherently bad. That's just dumb. That's said by somebody that isn't doing enough work.
Having no purpose is the function of art, so somebody else can look at it and ask a question. Design is different - you're supposed to understand what's going on. You can be delighted by it, intrigued by it, but you're supposed to know it's a hot dog stand.