it's not so many spam if you get used to it, I see bitcointalk as a crosstype of a forum and a chat 
so everyone is expressing their minds in short posts but longer then in a chat room if you know what I mean?
So, that makes it ok? Do you try to sell something to every single person you talk to in real life, or beg them to go to a store and drop your name so you get a kickback?so everyone is expressing their minds in short posts but longer then in a chat room if you know what I mean?
Do you wear branded clothing or eat and drink from branded packaging? Nobody is selling or begging you try anything here, nor is anybody forcing you to do anything. You can also turn signatures off in your profile.
that actually explained the situation the best way it could
a forum is like in real life, it's just that no one whines about shit like that in RL
a guy tattoes NIKE on his forehead and you don't tell him anything but someone sets a signature and everyone loses their minds..