The fact that the survival rate of startups hasn't improved doesn't show that our knowledge hasn't improved. Startups are competitive, with only 1 or 2 VC-scale winners per market. So, the claim is like "race car technology hasn't gotten better, because there's still only one winner per race."
Racing competition is flattened through regulation(oversimplified). All drivers have the same car. Drivers skill and fearlessness is the deciding factor.
I came here to basically say this about running a company- but your comment was a better launching point.
As someone who has run several companies over the last 25 years and has read and or tried nearly ever "method" mentioned... Im now running a company where Im abandoning everything and just going at with skill and fearlessness... and no funding. It feels freeing, and we are growing.