Alas, the practical reality is altogether different. Things in the everyday corporate world tend to go wrong. If the strategist has failed to correctly diagnose the problem, the strategy will fail to solve it. If the strategist has managed to correctly diagnose the problem, they might fail to convince others to agree with the proposed solution, and the strategy will fail to be executed as intended. If the strategist has managed to correctly diagnose the problem and
to convince others to agree with the proposed solution, there will still be internal interpretation and external interference by competitors, market forces and world events, and the strategy will fail to be realized as intended.
The list of things that make strategies succeed or fail is near endless, and many of them have nothing to do with the strategy itself. Just as a lot of companies make it not because of their competencies but despite their incompetencies, a lot of strategies succeed despite their faults as those executing it are able to work around the problems. The reason why we habitually do not to see the constraints, the surprises, the shit that happens, is because people handle them. Of course, conversely, a lot of good strategies fail because people are incentivized not to execute them properly or, for that matter, even at all. Few strategists take individual capability to act into account. Even fewer take individual willingness to act into account.
Planning also comes with an inherent predictability issue. While a number of companies undoubtedly have gone under due to their gross lack of foresight, many more have met their demise because they were unable to adapt to environmental change that they saw but fatally underestimated. History is littered with predictions of what would be yet never came to pass, but they are outnumbered by orders of magnitude by events that came to be yet nobody foresaw. Or for that matter could have been foreseen.