Well it depends on what were you using it for let me explain.
Let says I have an account on some #dofollowforum
where I managed to generate decent amount of posts and since each of my posts have a signature thus backlinks right. Now if you get banned you loose all of those backlinks which means that will have a negative impact on you website overall #SEO
Let take a look at #letsforum
that has signature rotator feature which means that most of your posts will have a different signature making your backlinks look more natural thus more effective.