This summary is not the rule. The rule text controls.
If a document has someone who signed it as a witness (called a "subscribing witness"), you don't need to bring that person to court to prove the document is real. You can use other ways to show the document is authentic, like other evidence or testimony.
The only exception is if a specific law says you must have that witness testify. In that case, you'd need to follow that law's requirement. But outside of those special situations, you have flexibility in how you prove a document is genuine, and you're not stuck tracking down every person who witnessed a signature.
