The point of the article is about how these latest crops of unknowns, with no connections to Hollywood, got in the front door by invitation because of their shorts.
Wes Anderson went to Sundance with a short film called BOTTLE ROCKET and got to remake it on 35mm as a feature.
John Carpenter won the student Academy Award in 1971 before embarking on feature films.
This year's Oscar's did a vignette on shorts winners who went on to make features.
The key I think is in the marketing and USING these opportunities to scale the walls and create demand. A lot of the examples had millions of views for their shorts online, a verifiable amount that showed executives that people are interested in the story and movie idea. They aren't interested in a good movie no one wants to see. If you make a movie and it "goes viral", as in millions of people show they like it by watching online, then you are not as much of a gamble with their money.
Creating something that goes viral and hits with mass audiences is still the key and not a guarantee.