why is だ so emphatic?

i’m curious as to why だ is always described as emphatic, assertive, forceful, etc in just about every learner’s resource.

after all it’s “just” a copula so what about it requires more nuance when it’s used? is it something in the etymology or is it more of a cultural/sociological reason? i’m trying to read through the tofugu article on だ vs です as well.

by onestbeaux