It was an attempt to decrease demand for the cards, thereby reducing price.
The simplest market solution to high demand and inadequate supply would be to raise the price of the cards. This would maximize short-term profits but Nvidia felt it was not the right strategic move. Why not? Here are some guesses:
- pricing gamers out of the GPU market would damage Nvidia's historical market - video games
- pricing AI users out of the GPU market would damage an exciting new market Nvidia is working very hard to cultivate
- tying a large fraction of your business to cryptocurrency is risky given the volatility of that market
I think Nvidia sees gaming and AI as viable long-term markets and feels very invested in maintaining the health of those markets and Nvidia's participation in them. They are much less interested in cryptocurrency mining customers because they don't see a long-term future for themselves there. Nvidia is willing to take a short-term hit to profits to get more of their products into the hands of gamers and AI researchers.
However Nvidia has not completely forsaken short-term profitability. They have substantially raised the price of GPUs and they are making considerable amounts of money selling GPUs to miners. They are trying to take a middle path and balance competing interests.