What "other games" did is completely irrelevant. This game's systems are programmed in a way that ties choices and consequences by characters to the specific campaign. Decisions you make have consequences in the world. For instance, tell a Tiefling she should get revenge, and her body appears elsewhere in the world later, you can walk to it without a single loading screen in-between.
Larian attempts to program their games around systems which always work, instead of needing to code custom exceptions all over the place which work in one spot and one spot only. Don't make assumptions about the knowledge of other people, just because you don't like the answer you're getting.
There is no reason that Larian couldn’t introduce a character import/export feature that just didn’t have anything to do with character choices.
If you import an existing character into a new game, you have a blank slate. Whatever choices your character previously made don’t matter. If you import into somebody else’s ongoing game, their choices matter, but there is no reason to import your character’s decisions as well.
