I don't know what it's effect on books is but it generated a lot of interest in bdsm and normalised it some IRL. I'm too young to speak for the before times from personal experience, but in the non-fiction bdsm books I've read they've talked about finding partners or opening up about it to be scary and risky. Whereas I'm just finding normal girls through normal methods (tinder) and "I'm in to bdsm" or "I'm a dom" has been met with either enthusiasm and interest because they're in to it themselves, or simply because they're open to giving it a go and don't have anything against it. Much like if I'd said I'm really in to cowgirl or some other mundane thing like a preferred position. Not at all the experience I've read about.