What would have been cool in S6 is if Andrea got onto a descent into evil path like Lena had done, but whereas Lena managed to come back from that, Andrea chooses to lean into it.
Like, if they had played up Andrea's hunger for ratings and clicks or whatever, and had done a whole bunch more shady shit earlier in the season, it would have set the stage for Lena to notice and come to her like "what you're doing is wrong, and I understand why you feel you need to do these things, there are better ways."
And then when Andrea finds Lex's poems, and had them typed up under William's name, she pauses before she presses the publish button. We see her think about what Lena said, see her weigh the consequences of going through with the unethical shit versus not.
Maybe she reaches for the delete button, and the audience thinks she'll make the right decision. But then we see her resolve harden and she presses publish instead.
After William dies, instead of Andrea going to the Tower in a fit of guilt, Lena is the one who goes to her at CatCo, and this time her compassion is nowhere to be found. She's angry.
"I warned you what would happen if you continued down this path," Lena seethes. "I told you--"
"William understood the risks of embedding himself with the Superfriends," Andrea cuts in. "It's no different than if he'd been killed while reporting in a war zone."
Lena's eyes flash dangerously. "No, it's not! Both of those choices would have been his choice. But you published that article under his name without his knowledge or consent. You put him in Lex's crosshairs! His blood is on your hands."
Andrea doesn't respond, but she doesn't quail either. She has no remorse, no guilt or sense of culpability. Lena draws back then, searching her friend's features.
"I would have been willing to help you, Andrea. But I can't help someone who doesn't want to be helped." She shakes her head, disgusted. "I don't know who you are anymore."
"Says the woman who tried to mind control the planet," Andrea retorts.
Lena's jaw tightens. "What I did was wrong. I will spend the rest of my life making amends for it. I only hope you have enough heart left to do the same."
With that, she turns on her heel and marches out of the office, leaving Andrea alone at the top of her dark tower.