pitifully they are necessary !, but tether should leave the market, there are other more transparent establishments like TrueUSD ... although the coins backed with fiat money is not the best! (it is as if it were the gold backed dollar), if the fiat begins to disappear, will they remove that support and print coins in an unlimited way? Is the story going to be repeated? ... I think a stablecoin backed by cryptocurrencies is better (it can be in bitcoin or another strong crypto) and that it can be verified in the blockchain