The American disability Act is a wide-ranging civil rights law that prohibits discrimination based on disability. It affords similar protections against discrimination to Americans with disabilities as the Civil Rights Act of 1964 which made discrimination based on race, religion, sex, national origin, and other characteristics illegal. In addition, unlike the Civil Rights Act, the ADA also requires covered employers to provide reasonable accommodations to employees with disabilities, and imposes accessibility requirements on public accommodations.
It was necessary for the Federal Government to force the states to have equality for disabled people in all public buildings and make the state governments pay for it.
This greatly effected the state and local government's budgets because the Federal Government forced them to apply the law immediately without any money given from the Federal level.
If this law was removed then people with disabilities would be limited to what public buildings they could go into. It would cause major discrimination.
Federalism plays a major role with enforcing this act because it would be difficult for the Federal Government to enforce this law nationwide because it would be almost too widespread to control. So instead they send it down to the state governments so it would be easier to enforce the law.