I believe that my interpretation is the most accurately descriptive of what they intended to say and what they hoped to advertise to people at the time
This is the observation that matters. None of us are on the dev team, so we don't know what code they wrote or why they chose to throw out so much of the PHB over time. But, the incentives behind their decisions are straightforward. Swen has been transparent about trying get the license for a long time. Larian has also prominently featured well-known IP from Baldur's Gate and 5E in their trailers, artwork, and advertisements. They have carefully courted the large, pre-existing customer base by sending messages that this game will be traditional and consistent with other official D&D products. What conclusion are most gamers going to draw about a product with an official D&D logo on it? Larian knows the answer to that. That is why brands bring so much value to developers. They know that the customer base will associate the ruleset with the logo, and buy the game.
