Most of the other ways require a trusted third party. The position of the trusted third party is attractive to rent-seekers and often generates conflicts of interest. Automating the position of trusted third party with an algorithm has value, not because the algorithm works better than a reliable third party, but because it doesn't have any interests of its own that could come into conflict.

Bitcoin itself is not at all the best tool for this job, its value comes from the fact that it happened to be first. It's valuable for the same reason antiques are valuable.