If we get rid of those "scientists" I'm sure they would be replaced by other organisms.
When an imbalance, like the disappearance of mosquitoes, is created, something worse could come about. There are examples of this already. For instance, the overuse of glyphosate and the sharp increase in the prevalence of things like Goss' wilt in corn, along with the increase in a new disease, that was never a problem before, call SDS or sudden death syndrome, caused by fusarium solani, a fungus that destroys crops and causes spontaneous abortion and death in food animals.
Ideas like this are usually about corporate profit, and control by regulatory capture. There are already in existence methods of dealing with infectious disease that do not require the extinction of 100 species of insects that may serve many yet unknown functions in the ecosphere.