My textbook says that it is not practically feasible to make insoluble salts (say PbSO4) from other insoluble salts (say PbO), without explicitly mentioning the reason for the same.
My guess is: if the product is also an insoluble salt, it may deposit on the insoluble reactant, and stop further reaction. However, isn't this problem solved by simply stirring? (Is the constant stirring required the reason why such a method would not be "practically feasible"? But isn't stirring rather common for chemical reactions?)
So, what is the actual reason?