I see your point, but allow me to add…
While certainly those groups existed due to a common bond, be it gay or skin color etc. But the groups lacked a lot of structure were able to assimilate into society. Certainly some things kept them back such as education, but they were still an integral part of our societal fabric.
BUT the GOVT had a better idea and they created classes of people:
"In United States federal anti-discrimination law, a protected class is a group of people with a common characteristic who are legally protected from discrimination on the basis of that characteristic. The following characteristics are “protected” by federal law:
Race – Civil Rights Act of 1964
Color – Civil Rights Act of 1964
Religion – Civil Rights Act of 1964
National origin – Civil Rights Act of 1964
Age (40 and over) – Age Discrimination in Employment Act of 1967
Sex – Equal Pay Act of 1963 and Civil Rights Act of 1964
The Equal Employment Opportunity Commission interprets ‘sex’ to include discrimination based on sexual orientation and gender identity 
Pregnancy – Pregnancy Discrimination Act
Citizenship – Immigration Reform and Control Act
Familial status – Civil Rights Act of 1968 Title VIII: Housing cannot discriminate for having children, with an exception for senior housing
Disability status – Rehabilitation Act of 1973 and Americans with Disabilities Act of 1990
Veteran status – Vietnam Era Veterans’ Readjustment Assistance Act of 1974 and Uniformed Services Employment and Reemployment Rights Act
Genetic information – Genetic Information Nondiscrimination Act
Individual states can and do create other classes for protection under state law."
However a look at these classes its almost impossible to not be a member in one or more. One has to ask, if we have a Constitution and the open line is “We the people” then why did the govt need to do this? The answer is simple: It allows the Feds/States to single out classes of people to bestow favoritism on and by the same token to deny another class of people or social engineering by the govt.
And by selective enforcement of its laws it can make one class superior to another…just as they have done!
Govt is ALL about CONTROL of its people…