DataDash breaks down Tether:
https://www.youtube.com/watch?v=kyQfGsYDcnw
I doubt Tether is responsible for 90% of the value in the whole crypto realm. It's a utility token to jump to the sidelines. I think the Tether issue is worrying, but rather blown out of proportion.
Of those who jump to the sidelines momentarily, many won't be able to buy back in lower than they "sold"? Which is to say it is less a force multiplier for inflating the value of cryptos, and more a mechanism for transferring money from noobs to the traders who correctly read the markets.
Many hodlers don't touch Tether or exchanges once they have bought their crypto. Are these people the majority, or the minority?
I think Tether should be shut down or implemented better, yes. My biggest complaint is that it encourages terrible behaviour. Noobs get rekt because of their weak hands, and veterans have a safe haven for high volatile periods.