possibly because it is very weird to even have that kind of market!
USDT is unofficially supposed to be worth 1 USD. in other words having a market to trade and assume there is fluctuations is against the very nature of this coin since technically speaking it should not move from 1 USD at all.
also adding such market can also cause fluctuations.
Well, Kraken wasn´t deterred by these concerns
I agree that fluctuations are against the very nature of this coin. However, fluctuations do happen
like when BTC is going to the moon again everyone sells their USDT in order to buy BTC, which
causes the Tether exchange rate to drop below 1 $ (because it doesn´t really matter
if you lose a fraction of your USDT value when you are making big profits buy buying into
a BTC bull run anyway).