I don't think that's fair at all. Perhaps as the seasons rolled on it became that way, but when Joan steps into Dynasty in season 2 she gives some truly brilliant acting performances. Her introductory scene in the courtroom is just wonderful. She looks stunning and her choices as an actress in how she moves her face, her mannerisms and gestures are just brilliant. It's so well done, old Hollywood. She pulls focus, she takes that courtroom scene and by god does she act the shit out of it. Equally her scene with Joseph in the art studio. So sinister and villainous, showing her true colours, which are very dark. She plays with him like the spider and the fly, or a cat toying with the mouse it's going to devour. Her first scenes with Krystle are again, equally brilliant, there is electricity seething from her. All the niceties crumble away and the true nature of Alexis petty, bitchy, nasty and angry character reveals itself. It's beautifully done, and not any actress could have done what Joan did.
It's also not really accurate to call Joan's portrayal of Alexis a soap opera caricature when really it was something that hadn't been done yet. Sure there had been bitchy divas on the daytime soaps before, but I don't think any that were even close to what Alexis was. Dallas had been on a few years and there was no female on that show that even compared. She basically invented the big soap bitch.
Joan Collins is not the greatest actress that ever lived, but she's a very intelligent actress. It just seemed like a mixture of a great stroke of luck and hard work paid off for her when she got Dynasty. She really seemed to identify with Alexis and her backstory and her struggles to succeed and she seems to have channelled all of that into the role. There's no doubt that Joan added a lot of depth and light and shade to what was originally written on the page. Joan created the look, and added her own British/European sensibilities to the role. She added humour also which a lot of the other cast were unable/ not allowed to do.
