You are onto it, the tax deductions associated with Steem will be a separate article. It's nice to see other people thinking these concepts! The equivalent to what an Uber driver could take as a potential tax deduction in the case of Steem is (1) business use of home (high risk to take this) (2) business use of computer (3) steem spent on upvotes/promotion/resteem services. This list is not all inclusive.

Another factor is whether writing for Steem is considered a trade/ business or a hobby.

The use of Steem acquired and powered up for the purpose of generating income. Well let me just say that's not an easy answer on whether we could take a tax write off for "depreciation" of steem power, but you defintely do have tax cost basis for the purchase of the Steem currency, so if you sell back for US money, tax basis reduces the gain. I would go as far to say worst case is that Steem Power on this platform is the equivalent of having land in the real world (it is permanent-lived and not depreciable but it has basis).