That's exactly the author's point. We still teach a cursive writing style that is better suited for fountain pens, while working with ball-points that require a lot more pressure to start marking. Being trained in a technique is not enough, if that technique no longer works with the tools that are widely used today. When I write with a fountain pen, I too find that cursive is more natural. When I write with a ballpoint, I actually tend to write in short clusters of one, two or three "joi ned le tt ers.", so my hand has a chance to relax between each... diglyph, I guess you'd call it.
Under the discipline of a schoolteacher, I could force myself to write "superb cursive handwriting", but when writing for speed and legibility, I adapt to the limitations of my tools.
Not writing in cursive helps but it doesn't solve the fundamental problem that ballpoint pens are significantly worse than fountain pens when you need to write for several hours in an exam for example.
Under the discipline of a schoolteacher, I could force myself to write "superb cursive handwriting", but when writing for speed and legibility, I adapt to the limitations of my tools.