Except that in the US, cryptocurrencies are treated as goods, and using them to buy something is considered a barter transaction.
For a barter transaction, you must recognize the current fair market value of the object received, and compare it with your cost basis of the object given. If the current price exceeds the cost basis you are required to recognize it as capital gains. (If below, you are generally allowed to recognize it as a capital loss, but recognizing capital losses is not strictly required, although in some cases there may be reporting requirements even if you chose not to recognize the loss).
Given the volatility of most crypto assets, there is a very good chance that the crypto is worth more than when you bought it, and assuming the goods are fairly priced, it would be typically be required to recognize the fair market value of the goods as current value of the crypto used to buy the goods.
Thus there is a meaningful burden imposed on people buying goods or services with cryptocurrencies.
Slightly different rules but with similar net effect would occur with respect to an individual us taxpayer buying things with say Euros, except that if the increase in value of the euro used in the transaction was less than $200, it does not need to be reported or taxed. Also for personal transactions the gains on a foreign currency are always treated as ordinary income, not capital gains, so no discount for long term capital gains will apply.