"different characters get wildly different stories"
Lol? Every RPG with a at least basic evil path does that better than BG3. WotR has its mythic paths, some which have a bigger impact on the story,
Because that's not what TC has said.
I particularly love character customisation in Baldur's Gate. You can make widly different characters, that behave widly different in the game, and again, there is a lot of choices and many reactivity to those choices
All of this is true. Especially systemic interactivity it beyond anything that we have seen in an RPG before.
I am not sure what you mean by systemic interactivity, but I've found reactivity in BG3 to be hit & miss, and sometimes very shallow. My Tav was a githyanki, and they are an example of this. You get a lot of [gith] options in dialogue, some very funny, but at the same time the githyanki quest doesn't really acknowledge you as one. This is because it was written with Lae'zel as the protagonist in mind. NPCs like Voss address Lae'zel as one of theirs, while my gith Tav was practically a third wheel in these conversations. Even though there was no story reason for Voss (or Orpheus) to ignore a githyanki character who was the actual party leader.
On a side note, by the time you arrive in the city, no one reacts to a githyanki anymore, so even that reactivity is limited to act one mostly.