Yes you are correct that if Darwin presented his theory today it probably would not be the great revelatuion it was 150 years ago due to modern scientific knowledge.
But image if the bible was released for the first time today. The same knowledge to would discredit some of what Darwins theories state would make the bible look like nothing but a bunch aof fantasy stories loosely based around actual historical events.
And any one that took it seriously would be locked up as a nut case.