Talking to someone while they still are in breakdown with a power out of control is not the same as getting through to them. They literally show her not understanding the torture people are in. The whole show is about her not being in her right mind. Grief + otherwordly power that goes out of control depending on emotions is a lot different. You are trying to compare this to actual reality and that's where it fails. She definitely needs therapy and her power could cause psychosis for her, but that's not really what they were detailing there. Just overwhelming depression. She was playing a role as much as everyone else in the town. And needed knocked out of the fantasy.
Again it was the five stages of grief.
Denial (the hex bubble)
Rage (lashing out at people trying to get through)
Bargaining (trying to keep onto what made her happy)
Depression (her overwhelming sadness)
Acceptance (when she finally was gotten through and realized what she did)
Again Purple Man was doing things on purpose. That's not what the show depicted for Wanda.
And she didn't attack them before lifting the hex. Her powers respond to her emotions and aren't under control. They act outside of her control. It's chaos magic. That's pretty much it's thing. She'll have to take up traditional magic to control it.