One material exchange got you: 250 glimmer, 25 rep, 5 marks, unknown xp amount. Now that's on top of the rep, xp and marks you earned while gathering mats. 1 hour gameplay for a farming run could generally yield: 4+ bounties, 6+ patrols, 2-4 events and 100 materials, 1-15 blue engrams (occasional purple). Now you return to the tower and either trade in everything or vault it. I vaulted everything and then used it when needed. The xp gains on mat exchange added up quick, especially when leveling new gear or a second subclass. The marks earned go towards more gear to use or break down. The point is, people didn't just run around farming materials.. Multitasking to get the most done in short timeframes. The loot and rewards could be as rewarding as many activities that require finding a team to do, without getting a team together. Plenty of coins, motes, engrams, cryptarch and faction level ups etc. Final point, it wasn't hurting anyone.