You kind of can do this by adding your signature after every bullet point.
Without adding multiple signatures, replying inline causes problems for detecting who is the author of the comments. Let's imagine that in your example, someone added a reply to the first point:
Here is my example comment in which I make several points:
- first point is a paragraph long
- Hello, I disagree! Signature2 time2
- second point is a paragraph long
- third point is a paragraph long
In conclusion this was my comment. Signature time etc
To our software (and also, to some of the people reading it), it will now look as if the Signature2 applied to the reply and to the first half of the original comment; and as if Signature only applied to the second half of the comment. This in turn results in confusing placement of [reply] links, and may also result in incorrect notifications being sent (we're planning to work on notifications next).