This works if a project is doable with a small team of smart/experienced people -- if it isn't then the methodologies become important

On any sufficiently complex piece of engineering -- using vendors to accelerate progress works until it doesn't -- there is usually a point very early in a product lifecycle where that starts to constrain progress/agility or limit feature development ... then there is another point later where it starts to bite financially ... then a point where the vendor gets acquired or ceases supporting it