Weird example. Slack didn't create a new space. They created a new product that entered a supersaturated space. Pretty much any VC would balk at a company creating yet another chat application.
> You don’t need to mention your GPA or that you once worked at Google.
You don't need to, but it helps.
...
Here is all you really need: build a good [great] product, get [paying] customers, get a little lucky. Other than the guy who got nixed from YCs HN Crowd selected funding program, it's pretty rare to have those three components and not get funding.
My cynical side reads this piece as an investor giving out, what appears on the surface helpful advice, but in actuality mostly benefits the investor by making their jobs easier by streamline the pitch process, so they can more quickly evaluate deals.