How does one measure social progress? Without an agreed upon definition of what is forward, how can we label something back?
Without such protections, people would be cheaper to employ because the deck is further stacked against them.
That is how we go back in time.
And maybe we could even break it down. Maybe protected classes for employment is great and maybe protect classes for service aren't. Or maybe protected classes for employment is actually regressive because it is endorsement of all the factors you can discriminate on. For example, orientation isn't a protect class (at least not federally), and thus in many places is legal to discriminate based on. Perhaps progress would be that employment discrimination is only allowed for factors actually relevant to the job, and adding protected classes is a regression from this.