Signatures are definitely a relic of the past. The rise of mobile makes screen real estate a lot more value so it’s unwieldy to let people arbitrarily fill up most of the space with junk.
However, what’s lost when signatures are gone is the ability to express yourself or your personality outside of your avatar and username.
So on my forum we tried to strike a balance by allowing users to choose from a set of small predetermined spirites. It minimizes space used while still giving people another way to express themselves.
Gone are open-ended signatures but we don’t have to throw out the full baby with the bathwater.