Given that any community will tend to develop established practice, the issue is a simple one: Does one wish to modify one's behaviour to fit in with the established practice of the community, or does one wish not to? Personally, I prefer the former course. Thus, I don't use signatures here, as established practice has them as unwelcome. Elsewhere, notably on Usenet, I use a variety of signature lines. A little time taken upon encountering a "new" virtual community can help one determine what that community's established practices are, and then one can decide if one wishes to accept those practices or not. While one is free to choose whether or not to do so, one should not be surprised if, upon deciding not to, one receives a less than enthusiastic response.