Yeah, but Reid was intended to be the "spoiler" from the start. The audience felt differently, but c'mon why would TPTB start to listen to the fans during the final months. They just didn't care and stuck with their plan regardless, like the endless Juicy Janet propping.
I would add that the power differential has changed between Sonny and Carly as the role has been recast.
Brown's Carly usually seemed insecure that she was Sonny's second choice after Brenda. It felt as if she was chasing Sonny to try to get him to commit to her. Brown's Carly came to Port Charles yearning for a connection after the difficulty of learning that she was adopted. From Bobby to Sonny, her motives were always written as if she wanted to hurt others as a defense against the constant fear that they might abandon her. This fit well with the manic energy that Brown brings to most of her acting parts, she always seems on the edge of breaking apart.
Whereas Wright's Carly has been pursued by other men and is no longer burdened by an insecure relationship with Sonny, because they share the bond of children together. And no matter who else they date, marry, or have children with, having Michael as their oldest child, and experiencing the trauma of his childhood, as well as loosing Morgan, has created a lasting bond that Carly never needs to doubt. Which fit well with Wright's cooler energy.
I think the status and power issue was present regardless of the actress. Mindy was the child of her business enemy Billy, as well as the step-daughter of her romantic rival Vanessa. And, as noted, Alex was sophisticated enough to know not to blame the mistress when a husband strays.
It would be like Roger Thorpe going after Ben Reade or Josh Lewis getting into a beef with A.J. Chamberlain, it would have been beneath them and broken the inter-generational code of civility on soaps.