> It's not the company's fault if I unthinkingly subscribed to their newsletters - they shouldn't have all their emails forever tagged as spam for my mistake.
It is. Default checked "subscribe" boxes during sign in, hidden settings, new lists which you are auto subscribed to; it's a never ending battle and the incentives are wrong. If there was no unsubscribe link but only the spam button, publishers would be much clearer about these things.
Ironically, the unsubscribe link has probably led to more spam, rather than less.