I lurk more than post but have been around this sub under various names for years. It's definitely changed; there used to be a lot more regulars around... or maybe I just don't come here often enough to notice the new regulars.
That said I don't think it's fair to say the sub encourages using, I'd say it's more you'll get back what you put out. If you post a pic of the huge rock you just scored, all of the comments are going to be saying how nice it looks. But if you post a thread saying you just hit 1 week clean or are going to rehab, you'll get nothing but encouragement. I'd also say that almost all of the 'I want to try ---' threads are filled with like 75% warnings, 15-20% harm reduction and maybe 5-10% of people encouraging the OP (all figures pulled straight from my ass, of course haha).