Why wouldn't this apply?

One day in the future the later version of sudo would become available...?

sudo has a bunch of commands and features nobody (except the person who implemented it) has ever used, giving it quite a large surface of attack. doas is meanwhile much leaner and developed by the OpenBSD community, meaning if a feature has security concerns it won't be implemented no matter how practical. sudo-rs somewhat of a middle ground between the two, not planning on implementing every single feature of sudo while keeping the same core commands and implementing the quality of life features doas doesn't like because they're insecure, and is the solution I personally use.

Subscribing to this question.

Is it better than doas?

Would something like 'doas' have the same issue?