As others have said, yes. But a/ it will take a lot longer (unless you get lucky) and b/ you'll have a worse selection of gear, limited to random drops, your Vanguard shop, and random Xur finds. Keep in mind that the majority of legendary vendors require Crucible marks. Note that you can collect materials (Spinmetal, etc.) and turn it in at Crucible vendors for Crucible marks, and wear a class item from one of the Crucible factions to transfer your rep there. It's technically possible, but really slow: 50 materials for 25 rep and 5 marks, so you'll be doing it for many thousands of materials. I can't imagine actually doing this, but it is theoretically an option. I've been stuck at 25 for ages, and I've finally given in to do Crucible. I'm also terrible at it, and I can't imagine anyone wants me on their team, but the call of level 26+ content beckons, and I don't want to spend tens of hours farming in the hope that I get something.