what you say is true only with respect to strongly secondary characters such as Theresa, Wanda, and perhaps Angel, where there is less involvement.
But on the other alternatives there is coumnque a huge problem of betrayed trust and fairly repeated omissions.
Let's take off the table right away the case that the gold digger was one of the "family" group, which would be morally a huge betrayal of MC.
but even sticking to the 2 main suspects there would be several situations to clarify. if the gold digger was Bella she would have continually lied to MC to manipulate him we don't really know for what purpose, we would have to question almost every word she uttered, every time she tried to make Elaine look bad, every clue she passed on to MC etc etc. she is probably the character who would become more difficult to trust in the aftermath of the revelation, she would really need a very good motivation to justify herself, and the legacy would not be enough to regain credibility.
to a lesser extent, however, this also applies to Jolina; the whole bankruptcy thing at that point would just be a set-up to get MC to help her, also a textbook manipulation. and given how central Jolina's economic difficulties have been to her history with MC, this would call almost everything into question, even without considering any malice in the matter of the security footage that would catch Elaine.