> Doesn't this simply mean that when people were selling their virtual currencies, they chose to stall their money in Tether?
Correct, and that's precisely how Tether helps prop up the price. There is a limited amount of actual USD floating out there to buy up BTC. People selling BTC in exchange for USD will lower the price. However two current trends can eliminate those sell orders before they impact the price. They are:
* They may be convinced not to sell, that they should hodl (sic) instead. No sell order occurs.
* They may be convinced to accept USDT instead of USD. No USD selling pressure occurs since they are willing to accept an IOU.
So why does Tether keep printing more? It's an easy way to absorb a portion of the selling pressure that wasn't convinced to simply not sell.