Of course it doesn't prove truth, but it does ensure that the data hasn't been tampered with since it was published.

For example, some powerful entity might be incentivized to try to change the text of old news stories to better support their current agenda. If you can change our understanding of history, you can potentially manipulate the future. Records that include proof of immutability will go a long way to making this kind of power play orders of magnitude harder and more expensive.