Question

It is best to limit your topic for all of the following reasons except:

Answer 1

to specify clearly what your intentions is.

For example, if your topic is too limited, you may run out of things to say, and people may not know what the general idea is

Answer 2

to get the point through to the people answering/being told.
as if you cannot limit youre topic, people may not be able to focus on one long enough to answer* it, and may end up not answering* anything at all.

*= im just using this word bcuz idk if its for a question or whatever, so yeah