At best they are a referral operation to the DOJ. And if a corrupt DOJ refuses to prosecute, then there is no one else who can. If the contemptuous party happens to be someone who can be impeached, even that is not a real threat since conviction in a democrat senate will not happen. So these days it is pretty safe to ignore or lie to congress without fear of consequences.

I mean, that's not just a claim about lying to Congress. Most federal laws require federal enforcement - especially criminal laws. Congress doesn't just lack the power to enforce contempt findings. It lacks the power to enforce any federal law. It relies on the Executive to do that - and the DOJ for all criminal cases. If the DOJ doesn't prosecute substantive federal law (not just subpoena issues), there's no one else who can, either.

So if you stipulate a "corrupt DOJ [that] refuses to prosecute," then it's not just lying to Congress that's an issue - it's all federal law altogether. If DOJ refuses to prosecute wire fraud charges against Republicans, or counterfeiting charges against Democrats, then that's a bigger problem than just the tiny aspect of subpoena power.