A tractor that is 70% as good as a Deere won't sell on an open and competitive market where people vote with their dollars.
Perhaps, but the point is to make a tractor that is 70% as good as a Deere, at less than 30% the cost of a Deere. This project is not targeted at industrial farms, or people who do large scale farming as their primary occupation. The equipment is currently targeted at the "want to grow my own food, and have enough to actually feed my family" more-than-hobby scale, where hand tools are insufficient, and the price of professionally built equipment can be a huge barrier to entry.
When the smallest Deere tractor you can buy costs you over $16,000, and after spending that much you still don't have any implements to use with it to actually get work done, having a cheaper alternative starts to look more attractive.
Also, if you had read the article, you would have noticed that they ARE working on a plan for building and selling enough construction machines to have the farm turn a profit. They're just sharing the blueprints so that other people can do the same.