This is purely opinion and I come in as an ancient and more or less retired entrepreneur. The start-ups I was involved in and was part of the founding/early stage funding were funded by the the grand early on venture capital firms such as NEA under the guidance of Dick Kramlich, Kleiner, Perkins with Gene Kleiner on my board , Hambrecht and Quist with Bill Hambrecht on the Board, etc. In all cases the Board of Directors shared their wisdom and were proactive in watching us young guys like hawks. When they saw any exec. ignore advice and go rogue with immature behavior, there was never any hesitation to fire the CEO and re-engineer the management. They also understood the power of "Dry Powder". Meaning if the start-up progressed positively the investor's were always prepared to fund follow on rounds or walk if the company looked like it was in failure mode due to inept execs. management or bad attitude.
Hence, I lay the blame of many of the hot shot start-up failures at the feet of the Board of Directors who are often as inexperienced at managing business situations as the entrepreneurs.