All the work the author put into this piece, only to be undone by its basic premise. That computers can play an active role in cognitive development. The author is correct when he states that that computers have never found a place in mathematics curriculum. Not even after the last 60 years of their existence. Even after an uncountable number of attempts. And it will be true for the next 100 years.
Yet, those who do well in mathematics have had no problems using a computer, or a spreadsheet, or a calculator.
One thing should be certain in any educator's mind, and it is in most. Computers have nothing directly to do with teaching mathematics. Art will never derive from the tools the artist uses.
Teach the students mathematics and reasoning, and you will not have to teach them how to use a computer.Bob Hansen