People often conflate diversity for inclusion. Diversity isn't an integral part of a business's success because diversity alone is meaningless. It doesn't work unless you also have inclusion.
Having a diverse workplace without instilling a culture of inclusion doesn't allow the benefits of diversity to filter through. Imagine a scenario, for example, where you have a team of equally represented males and females, with a wide spectrum of ages, backgrounds, and familial situations. You have equal representation, but if your company still schedules meetings at 6pm each evening, those with children will not be included and unable to participate. Representation (i.e. diversity) is just the first part of the solution. Inclusion and participation are necessary to actually unlock the benefits of diversity and drive a company's success. Simply having diversity without taking steps to foster inclusion and participation creates a compliance mindset and makes minorities feel judged rather than valued.
[P1] Diversity is not enough. To unlock the benefits you need diversity and inclusion. [P2] Therefore, diversity is not a critical component to a business's success, inclusion is.