I believe it's not as clear cut as that. I believe that in many jurisdictions there are various rules that allow trading within certain assets classes to not be treated as a taxable event for capital gains purposes unless you trade outside the class back to a regular currency. The taxable event can occur only when you realise the profit or loss.
Whether this is the case with crypto currencies is all dependent on how your particular jurisdiction has chosen to classify crypto. Or often just your best guess if your particular jurisdiction hasn't been clear on the classification as many haven't.
Nope, it is that clear cut. Some coiners tried to convince the SEC crypto-to-crypto exchanges were like kind 1031 exchanges and the SEC had none of it. If you've been under the impression it was not a taxable event, you should solicit a very competent tax attorney to get you out of whatever hole you're looking up from the bottom of.
It's never been that way in the US. Sale of any cryptocurrency for any other or any asset or even a cup of coffee has been a taxable event since the beginning.
You realize a profit or loss every time you transact, and that's a taxable event. It's not tied to whether or not the transaction is into or out of fiat currency.
Whether this is the case with crypto currencies is all dependent on how your particular jurisdiction has chosen to classify crypto. Or often just your best guess if your particular jurisdiction hasn't been clear on the classification as many haven't.