Why were rockets not extensively used throughout the world like cannon until the 20th century? Maybe one may ask the reason for pointing out 20th century. I guess it's fair enough after thinking about sailing ships full to the brim with cannons or star forts which were built to withstand heavy cannon fire. Even in WW1 rockets did not play an important role.
I am not saying that they had never been used. Numerous military leaders (from Mongol commanders to British ones) made use of rockets in naval and land battles including siege warfare for both offensive and defensive purposes. But in the end, rockets were never as popular as cannons despite being invented around the same time and rocket's explosive/incendiary attributes - even for early rockets.
One reason would be the inaccuracy problem encountered in rockets.But in return, especially early cannons and their ammunition were extremely heavy (see Dardanelles gun); from a logistical point of view they should be nightmare for users. I can add some other poor attributes of both, but I think that much is enough to make my question clearer.
So, both (rockets and cannons) seem to have some disadvantages when compared to each other. Then, returning to where I started, why? Also, is there any surviving handbooks or training manual for soldiers of those days which compare such fire support weaponry or clearly favors cannons over the rockets?