This makes it useless for getting a confession to a crime with no corroborating evidence. However, if you have a method of independently verifying the information you get, you can get useful information.

Note: I oppose torture, but effectiveness is orthogonal to my opposition. Something can be effective and still evil.

Not that effective for gathering reliable intelligence in a timely manner, but very effective for other purposes: To punish, to instill fear in potential enemies, to satisfy a need for revenge.

The "gathering intelligence" excuse is used only because it allows "good people" to convince themselves they support torture for rational, "good" reasons. Nobody would openly say they support torture because they want to see the enemy writher in pain and fear and be forced to eat their own shit. Even if this is the real reason.