You can simply see the history of algorithms over the last two decades. Look at things like RC4, which is notoriously hard to use safely. It had a history of many issues and was ultimately abandoned even though you could theoretically use it securely to this day. It is situational, but with cryptography, algorithms are deprecated from an abundance of caution in many cases. It’s a little different with a protocol and not a foundational algorithm, though. We can often correct a protocol in a safe way compared to an algorithm that is often simply deprecated. Still the sentiment is mostly correct, but perhaps a bit overstated.