There are a lot of charlatans in the consulting business, particularly in leadership training.
Many consultants jump straight into fixing, diagnosing a problem in leaders and prescribing a solution. Worse, many consultants generalize the problem or problems they see most often into a theory about why leadership is ineffective, and prescribing a generalized solution to all leaders to implement a specific action or tactic.
This doesn't work because every person, every team, every challenge, and every environment is different. Moreover, they are all changing - constantly.
Don't think that this is new, either. Many people will tell you that the business climate is fundamentally different than before, so we need different solutions. History shows plenty examples of the kinds of change we're going through now, and leadership hasn't changed. It's not like someone invented a new human a decade or two ago.
This is why understanding the concept of leadership in a way that crosses over all situations - in other words, being able to define leadership - is the critical first step to determining the appropriate solution for any specific environment or situation.