Author here. I should have been more clear about this in the article, but it was a combination of two different factors. First, the company alienated OEMs by making their own cards. Second, the cards they made were close in price to ATI and Nvidia offerings while being slightly less powerful. To make it worse, they were struggling to produce, and so while they had some interesting hardware in the works, they couldn't get it to market quickly enough.

Nvidia did sprinkle 3dfx's technologies across their products where it made sense, and many of the 3dfx folks continued at Nvidia for some time.