Has anyone ever written a paper and put your name on it?

Without knowing too many details of your situation, could you perhaps give the other author the benefit of the doubt? Cutting off all contact does seem harsh (unless you have other reasons) for what could simply be a misunderstanding.

I don't know the conventions of your field, but it seems in many science fields that authors are added if they contribute intellectual ideas on the research, not necessarily for doing the research. Other authors simply add support in some fashion, so get added. It is not uncommon to have many authors on a science paper. It does in fact get tricky because one can offend others by not including co-authors.

I'm of the opinion that it's probably better to include someone who contributed in some fashion than not include them. You could argue that this dilutes research and is a "pure research game", but honestly, one paper is not going to make or break anyone's career.

Could this author simply have been trying to extend kindness, or perhaps thought you had a bigger role in the research than you actually felt you did?

I have heard stories about some (mostly weak) young mathematicians include the names of some people (influential enough) to facilitate the acceptance of their papers or to help them for employment, grants, etc. In fact, two years ago, an almost innocent case of this was going to happen to me. In Iran, most departments of mathematics have this (written or non-written) rule that a master or a PhD student should have at least one paper with his/her supervisor, otherwise she cannot graduate or she misses some points from her thesis grade. I had a master student and she wanted to get the highest grade and therefore she asked me if I allow her to write a weak paper and include my name as a co-author of the paper. I deny it and she missed 1 (out of 20) from her thesis grade. Of course, to compensate the 1 point unfair reduction, I defended her and asked the jury to not reduce any more points from her grade.

To answer your stated question: the only general requirement for your authorship on a paper is that you contribute to the research significantly, and that generally doesn't imply co-writing it — contributing to the ideas can be significant, especially if the proof becomes trivial with an idea you contributed. (I've heard mathematicians describe "significant contribution" very differently — say, that PhD students are expected to draft papers, get advising and feedback from their supervisor, and not list their supervisor as coauthor — unless the student failed to contribute to the project).

Now, you have similar ideas. In my experience, tracking down who originated an idea among people who did work together can be very hard, and joint credit can be an easier solution which is accepted in our community (in Computer Science, Programming Languages).

However, since all authors are jointly responsible for the claims in the paper, I've been taught it's very bad style to add somebody to a draft without his permission; submitting the paper without your knowledge/consent would be unethical, but dropping contact is not only brisk, but ambiguous. Couldn't he genuinely (in good faith) think you were okay with the draft, but didn't have time to respond?

In fact, if he thinks you contributed to the research, to publish it ethically, he'll need either your agreement to have your name in, or your agreement to have your name out.