What is one significant issue with using Flash in web design related to accessibility?

Using Flash in web design presents significant accessibility challenges, primarily because Flash objects can trap keyboard focus. This means that when users navigate through a Flash interface, particularly those who rely on keyboard navigation (such as individuals with motor disabilities or visual impairments who may use screen readers), they may find themselves unable to escape the Flash content or access the rest of the webpage. This entrapment can severely disrupt the user experience and hinder the ability of individuals to interact with web content.

Ensuring that all web content is accessible to individuals with disabilities requires that navigation be unobstructed and that users have full control over their navigation methods. Trap focus in Flash undermines this principle and poses a barrier to equitable access to information.