Honestly, I don't think there was even that much marketing for Divinity Original Sin 2 either.
I remember when BG3 got shown off at the Game Awards last month, most of the general gaming community in the stream chat just laughed at how out of place it looked compared to a lot of the more traditional games shown alongside it. People were calling it a tech demo and shit.
At that point, I think Larian would want the game to rely on word of mouth and rave reviews more than anything else, same way as DOS2.