Let me summarize something.
You don’t disagree the cost of maintaining indexes as this blog describes.
You are not disagreeing there are “some” costs for innodb either.
So there is a flame MyIsam vs. InnoDb left. Which is imho not intended (at least from the author).
Btw: Im not working for fromdual, so I don’t give a ***** what they do. If you want to read my homepage just click on my name;)