[laken]

In addition, it's more "liquid" too. It's easier to turn tether into pretty much any altcoin on most exchanges vs turning USD back into altcoins.

There's still a belief in some circles too that a crypto/crypto transaction isn't a taxable event, which isn't true anymore. Regardless, some either believe this or know it's not true but find it easier to tax-evade this way.

[ska]

  which isn't true anymore

It's hard to argue it was ever true, or ever likely to have been treated as such.