For world knowledge, you'd want it to find and reference the source material to be sure. At that point, it doesn't matter if the knowledge is embedded.
I think the big models have adequate recall, so tool use is probably unnecessary, but the user said the correctness of my response is important. Let me look up the data instead of relying on my memory.
World knowledge also means knowing the various algorithms and ways particular programming problems are solved.
You can't search what you don't even know exists.
Keep in mind a web search might not include scanned books baked in the weights ;)