It's similar to the point of issuing a subpoena, except instead of being issued by a Committee, it is issued by the entire body of Congress, the House. It's an escalation of threat - for whatever that threat is worth - with the ultimate power of the House being to bring articles of impeachment.
One might ask even what is the point of impeachment, since the Senate won't convict.
The House holding a person in contempt is non binding too.
>>Can someone explain the point of a nonbinding resolution?
Pretext for EO Release by WH?
The point of that is from U.S. v. Nixon (1974), a 9-0 decision of the Supreme Court which held that there is no Executive privilege in an impeachment trial. All requested documents must be turned over. With what Q has said about [RR] having to resign or recuse if what is in those documents is revealed, the need for conviction should not be a factor.