For many things. Change .epub to .zip for example, you get html text and jpg images

.docx and .xlsx are also just zip files with XML and attachments. The bad thing is that the XML is Word's internal document structure serialized and behavior for some values is only defined in Microsoft's code.

Sometimes you also find hidden things lurking accidentally left behind in IPAs and APKs that are nice and juicy and realize they've been shipped on Google Play/App Store for years.

I've found everything from entire copies of internal company manuals to working test credentials for a physical place with a membership barcode in debug logs left inside the app from developers.

Also sometimes changelogs left inside by accident which include things like "It hasn't been sanitized for outside consumption and thus should remain internal to <company>. Deliver it externally at your own risk of embarassment."

The elites don’t want you to know this but the distribution file formats on the web are zips you can just unzip them I have 458 zips.

It is zip files all the way down

They are typically encrypted, though.

Wait till people discover file(1)!

Indeed so