It’s also a rare example of where a massive budget without restrictions (relatively speaking) can lead to amazing results.
Usually one of two things happens: the publisher is tired of dumping money into a project then force it to market too early, or scope creep happens and the developers bite off way more than they can chew and there’s nothing they can do past a certain point.
Larian managed to dodge both of these bullets. Not by luck, of course. But they dodged them nonetheless.