its sufficient that in a group of 1000 nodes, 500 save backup of 50% of the data (Type A node) and the other 50% can save backup of the other 50% of the data (Type B node), its a waste of space all the nodes in the network save all information repeated thousands of times.
Then each node Type A can "ask" to other node Type B the information is trying to find and vice-versa and gets the information anyway
Bitcoin was designed to be trustless. The idea of running a node is that you can validate and verify every single transaction yourself. If you run a Type A node, you would have to trust the Type B nodes to do half of the validation for you. If you're going to do that, why not just trust Visa and forget all about Bitcoin?