Every story has to have a hero and a villain. Harlots, a show that puts women front and center in the world of 18th century sex work, happens to have a female villain as well. Of course, these women are fighting a particularly oppressive patriarchy at any corner, but the awful way that Lydia treats other women on Harlots only strengthens the show's message by juxtaposition.
Not only does Lydia treat her girls more like indentured servants forever indebted to her than actual employees, but the way she kidnaps virgin girls and arranges for them to be raped by clients is particularly heinous. This is more of what modern society might define as sex trafficking. They are hired as housemaids under horrifyingly false pretenses. Lydia selects her victims with a precision that reminds me more of a serial killer than anything else. These girls are innocent, desperate for work, and most importantly don't have any family that might come looking for them. It's awful that she's doing this just to serve a male client with a that kind of sexual proclivity.
Lydia is also actively trying to take Margaret Wells down. Competition is good for business, but this is a step to far. Plus, fact that Lydia's brothel purports itself to be higher class than Margaret's just adds insult to injury. They may look and sound nice, but the "House of Delights" has a much seedier underbelly.
Of course, Lydia Quigley is also a female business owner who is making her way in a society pre-women's rights. Just like Margaret, she is struggling and succeeding to make a living and maintain her own autonomy. But by taking that power away from other girls, Lydia is going about it the wrong way.
The best way to tell a feminist story is with variety, in my opinion, and for that reason I think it's smart that Harlots has an antagonist like Lydia Quigley. It's not pitting women against women in a way that we might view as problematic in any other story.
Plus, in Episode 4, the weight of what she is doing to these girls seemed to finally hit her. Lydia Quigley is as complicated and as multi-faceted as any character on this series. I think there's a chance that before Harlots is over, these two feuding women might end up on the same side after all.