I'd add that while the Author is correct--bokeh is a property of images, not lenses--its not materially different that how most photographers understand the term. While a lot of photographers may say things like "that lens has great bokeh", they don't think that bokeh is some quality in the lens. They are just shortening an idea lke "this lens produces images with great bokeh." It is a lazy way of rephrasing it, but I have never met a photographer that thinks bokeh is not referring to the image.