Well, plus then you really would have a huge barrier to entry for anybody coming into the series with later installments. There’s enough to learn about the war and which side the Champion took in it without having to worry about creating an extra game within the next game for starting a temporarily averted war and hoping newcomers aren’t totally lost.

Plus I’d rather not have to replay two games multiple times just to experience everything in the third.

I really wish they would diverge more. Ideally by the third game in the series there should have been enough branches that you could essentially start in and play through two completely different games, based on your choices in the first two (ie. one in which the war between mages and templars is happening and one in which Hawke averted/delayed it). Unfortunately that would probably be seen as two much work for no extra money.

If you can lose access to things based on previous choices, this is going to happen whether you use the Keep or not. The game will have to give you a default world state. It’s not possible for there just not to be one. The only difference is that you won’t know what choices were made for you.

I don’t think much will be “blocked off” based on previous games’ choices though. In DA2 things that changed were, like, if you encounter this former werewolf character (based on whether you slaughtered or saved the werewolves), or how people talked about the Warden. I highly doubt anything would be legitimately blocked off, beyond some dialogue differences and cameos.