"is there (for now) any social media platform that makes it possible to earn money by posting, commenting and up voting posts like steemit?" thought you already answer that and in response to the question that's asked "Do you agree?" I do agree, steemit encourages more people to post more thoughtful content, because here in this platform, often only the most interesting content survives. But i think that what steemit advertises itself as an platform where you can earn money by doing multiple things, it also attracts people with the mindset of coming here and registering in hopes of making money, and but often they will realise that its not so easy here to do so. They will either be disappointed and leave or Stay and start to learn the inner workings of how steemit work and start to build up reputation and effort to create good content that steemit so lovingly desires.