Letting alpha males flourish can seriously damage a company not just because it might create barriers to diversity but also because there needs to be a culture of learning, self-awareness and prospective of self in relation to the entire organisation.
The problem here might lie with the fact that alpha males tend to surround themselves with similar characters and without debate, different perspectives and approaches the team won't be able to achieve what they want to achieve.
The best way to deal with personality type is not to tackle them head on (they thrive on conflict) but to subtly dampen there excesses and harness their strengths by making sure they are part of a team populated by other styles.
Do you know any Alpha Males in your organisation, maybe intimately? ;-)