@JB,
The author is making a very valid point, even if you don’t like his wording, the the potential savings from the better pricing online could easily be offset by the tendency to overspend because of the tendency to overbuy.
It’s actually a very narrow point, which merely addresses one possible advantage of having internet access.
The Lakewood “takanos” specifically address the fact that better pricing online is not considered parnassah, and I believe that this may be the reason.