I guess you did not click or open the link I have provided therein for everyone to read more about the controversies, that says 'Tether is used to provide price support and manipulate cryptocurrency prices'. John M. Griffin and Amin Shams, both from the University of Texas conducted the research published a paper (via Business Insider) that makes a remarkable claim, according to this report, http://bgr.com/2018/06/13/bitcoin-price-today-vs-ethereum-vs-ripple-vs-eos-manipulation/