To highlight how nuts this could be: I travel to India every year, and I always carry with me a few hundred USD worth of rupees (the local currency). It would be insane for me to try and track the value of the rupees (in USD) for every time I bought something, and calculate the deltas between that and what I originally gave to the money changer. It is completely impractical to do that, and while I'm not an accountant…
The IRS has decided to treat cryptocurrency as an asset (like gold) instead of a currency.
So why shouldn't the IRS do the same?