So if a new manager is able to mess it up, the system was necessarily weak? Not sure I agree.
Looking at the context the interviewer asked about a new CIO coming in a gutting the management system. I said if they have a strong management system that can't happen. Executives can't just have whims (usually driven by a desire to "make their mark") that throw out the principles used to manage the company if there is actually a strong management system.
Most organizations just float with whatever fads are going on, so in most they can flip flop as new executives come into place.
On the question of new managers making mistakes. Yes, I agree they can. Once again good management systems make a significant effort to bring new managers up to speed. Those management systems reduce the likelihood of failures created by new managers making mistakes. Again, most organizations do a poor job of brining new managers up to speed: Toyota does a good job, the USA military does also, Costco does a good job, I think P&G does (but my information could be outdated). Many others do this well, but the majority of companies do this extremely poorly. That is a serious failure of a management system and I would put more of the blame for those failures on the poor management system, that the managers making mistakes when they were put in a position they shouldn't have been (being made responsible without proper preparation).
Related: Poor Results Should be Addressed by Improving the System Not Blaming Individuals - Management Training Program (2005 Curious Cat post) - Curious Cat Management Improvement Dictionary