What do you suppose they should do to the original authors? Perhaps the original author is Claude Garamond who died in the sixteenth century? Or the unknown workers who carved the inscription at Trajan's column in the second century AD?
Everything is derivative, there is nothing new under the sun, and your argument proves nothing.
Sure, but with fonts you have basically one level between the font they are 'developing' and the one they are copying from. There is work involved, but very little of it is creative work.