Dreamland, comments such as yours do nothing to show any of us readers that you have very much idea about where the responsibilities between controllers and pilots differ. Calling a tower controller a "nugget" because a pair of pilots made a fatal error only shows you to be one of the many enthusiasts that populate this site and habitually engage foot in mouth whilst trying to somehow show us that you know something about our jobs when in fact you know sod all as you have just proven.
And if the visibility had been marginal and the runway not visible from the tower? Would you expect the pilots to be refused take off clearance? Of course not.
It is nuggets that assume that what a controller can see from the tower cab is somehow crystal clear and floodlit that is the problem here. Those pilots made a fatal error and hopefully the rest of us will learn from their mistake. The tower controller was not responsible for the pilots error you nugget!