The more senior the person being asked, the more likely they're working on something complex enough such that the delay incurred by an interruption is non-trivial.
* Is the person asking actually blocked?
Often times, people get into a mode where they will interrupt others to ask questions they could have answered themselves with a little additional research.
* How important is the blocked task relative to the delayed task?
More often, the person asking the question is more junior, making it likely they're working on more trivial tasks. The person being asked, often more senior, is more likely to be working on more valuable tasks. It's possible even a slight delay in the latter's task is a greater cost to the business than leaving the former person's task blocked.
As an extreme example: you don't want an intern interrupting someone trying to resolve a downtime event just so the intern can get unblocked on a throwaway project.
The problem is, having a well-organized and cooperative team massively outweights having a bunch of rockstar developers each pulling in their own direction, unless we're talking about the tiniest of organizations. And I'm not going to be on friendly terms with someone I'm not allowed to talk to.
* How minor is the delay?
* Is the person asking actually blocked? * How important is the blocked task relative to the delayed task? As an extreme example: you don't want an intern interrupting someone trying to resolve a downtime event just so the intern can get unblocked on a throwaway project.