There are good reasons to ask for a link to a questioner's blog.
Sometimes people are in this forum and don't understand that there are 2 kinds of WordPress with completely different options and capabilities. Check out the difference for yourself here: http://en.forums.wordpress.com/topic/please-read-me-first-before-posting?replies=1 so you won't waste your precious time and intellect answering with something that does not apply.
Sometimes people have their blog and nickname linked, but are asking a question about another (unlinked) blog. And especially if the answer to a question is theme dependent, volunteers can waste a lot of time with irrelevant information.
If you can't see the questioner's blog, then in reality you are only guessing at an answer that is useful.
Also, some people are such new bloggers that they don't know that they can link their names to their blogs. That has bennies in these forums for us, and also for the bloggers: when they comment on other blogs, others can also find them (and they don't appear as spammers leaving blatant links all over the world).