The writers could have sold Steffy and Hope as sisters if they had stuck to the history of the show, and evolved the SL over time. Steffy, Phoebe, Hope consider themselves sisters. Phoebe dies. Rick uses Steffy to get back at Ridge. Steffy finds out what Deacon and Brooke did to Bridget (the aunt Steffy, Thomas, and Phoebe adored). Stephanie, who always loved to twist the facts to suit her narrative, could be pouring venom in Steffy's ear about Brooke and everything Brooke did to try to get Ridge away from Taylor. However, Ridge always turned Brooke down, and Stephanie could paint it as Brooke took advantage of Ridge's grief over Taylor's death to finally get Ridge. Taylor returns from the dead, but Ridge has to stay with Brooke because of RJ and Hope (not true, but the truth didn't exactly matter to Stephanie). So Steffy decides Brooke, Rick, Hope, Katie, etc., are the enemies. This begins the Steffy/Hope rivalry. However, after Steffy finds out Taylor shot Bill in the back she realizes she doesn't want to be like Taylor, Brooke, and Stephanie, makes peace with Hope and moves on from Liam.
Instead we get the constant lie of Ridge left Taylor and their children to go be with Brooke which NEVER happened.