In some cases, e.g. the history of Native Americans, it often is necessary to ask for clarification on the time-frame since due to education and the way popular media portrays the subject, sometimes people tend to lose the sense that Native Americans are still people today and have a history spanning thousands of years before the arrival of Europeans as well.

We generally remove answers that contain only pedantic corrections like that, but also there are times when that's necessary to set the scene for what we know and can answer. For example, in a question that asked How well armed were merchant ships compared to warships in the Age of Sail, it's necessary to say "here's the context I'm answering in," because there are merchant ships and warships (and some that blur the line) across the world, but my knowledge comes from northwestern Europe and the Atlantic world.

1. I have a long track record in this sub of taking "medieval" or "ancient and medieval" or "premodern" questions, often where other users have jumped in and said "Be more specific" without having any intention of answering, and answering the question based on my own area of knowledge.

2. There is a difference between asking for specificity when it will help YOU write a better answer or one more satisfying to OP; and demanding specificity to be a standard-fare reddit pedant.

3. You'll notice in the Canada winter thread, I did provide an answer concerning a specific context. I've been on AH long enough to know, as /u/commiespaceinvader says, that "Native Americans" questions mean pre-colonial. Because we have a tendency to view Native Americans as time-locked in the past. This is a pernicious ideology that disguises the ongoing oppression and cultural genocide against Natives today. When you consider why I opened by asking for clarification on a time period while emphasizing Native populations today, please take a moment to reflect on the points raised in this paragraph.