In answer to your question:

Yes.

Not that I particularly have a problem with you assuming that you know me, my wants and desires and thoughts and feelings without actually conversing at any length with me in person. However, some people take offense to the idea, and especially at the assumption. Because you do not, and that's simply the truth. You cannot honestly know just about everything about a person at whim or presume that they will taell you something that is not immediately clear.