Eliminating pruning was possible, because there are only about 40 moves in a position. In the game of Go, there are up to 361 moves in a position, so even computers must forward prune. An early Soviet program could consider certain moves as analogous to moves that had been found to be bad in a parallel position. It would prune them unless something was observed that would rehabilitate them. This also was abandoned.
Present programs spend most of their time rejecting the same moves millions of times apiece.
Human chess players often partition a position into subpositions, for example the king's side and queen's side. We analyze the subpositions somewhat separately and then consider their interaction. Present chess programs only consider the position as a whole, and computer power makes up for the inefficiency. Computer Go programs are weak, because partitioning is absolutely necessary for Go. We still don't know how to make computers partition effectively.