Unfortunately I could see people abusing this to the point of it everyone being stacked and maxed in a day or two, and those "playing honest" and doing it by themselves get left in the dust. Not to mention all the scams of people trying to sell their stuff for real world money, and then not delivering on their promise when the paypal goes through but they never receive their merch. The Mythoclast is meant to be extremely hard to get, and as such be a dominant weapon (even after the nerf) for those with the skills (or in the current situation, glitch knowledge of bumping Atheon off the ledge) to get it. How broke would this game feel if every multiplayer match was going up against a team of lvl 20's with maxed Mythoclasts because they bought them on Ebay? The best option we can hope for from Bungie would be for Xur to offer the ability to buy an Energy or Shard for either light and/or coin (as most weeks he offers the same crap anyway). If I'm gonna spend 17 coins or 23 motes to get an exotic engram to break down for 2 or 3 shards, I'd rather spend 23 motes to guarantee getting 4 shards or 4 energies (that leaves the player with the decision to gamble on getting something they actually want to keep, versus just buying the energies/shards they need). The next best is to use the system that is already in place for you. Build 3 characters, and then you can have multiple lvl 26+ characters that you can use to do daily/weekly/weekly nightfall/gold tier events and raids with, getting 3x the loot. That's what the vault is for, to transfer stuff like weapons/shards/energy/etc to your primary account, while using your other two accounts to farm. The initial work would take you about 2 weeks to get all of them into the 20's, but once you can do the weekly/nightfalls, we'll all then be complaining about not having anything to upgrade with all those shards/energy (have your buddies do the same, then you can each use your primary account to help the other's farm accounts beat the weekly and weekly nightfalls, and you all benefit and get more stuff).

My friend even ask me for some legendary weapons that I keep getting so they ready for raids or just have the weapon if general.