Destiny pre level 20 is a totally different thing, everyone is on the same page up to that point. It's like waiting until you're 16, 18 or 21 to get a job or be able to go to the Casino, up until that point everything is pretty much given to you. Bungie who in a sense would be like your 'parents' provide for you as you go, by playing the storyline you get armor upgrades weapon upgrades, it's like your parents buying you clothes or new shoes that fit better. Until you turn 18 and the turn you out on your own where you go to work, run the daily, bounties, weekly and eventually the raid and nightfall. I hope you can understand my analogy.