A literary agent I follow told the story of a long argument her autoreply had with a would-be author. She’d set up the outbound email while out of town and apparently an author who queried her with his book took offense to it. He replied back in frustration that he didn’t get a personal response. Her autoreply sent back another automated message, which he then in increasing anger kept responding to.
That’s basically my OOO message also. I’ll admit, I haven’t checked my office phone in weeks for VM, because anyone internally (or externally with any brain) would IM or email, and any spam calls can just sit in my VM.

This is what I’ve seen most often in my career. Problem is, the contact is almost always the admin. I’m the admin. Everyone’s idea of assistance is different. Often, I didn’t have the knowledge about the issue in order to be of any assistance. I wound up spending more time running around looking for answers than actually working on what was on my own plate. It’s exhausting. Otherwise known as “please don’t call us for unicorn problems when we handle llamas. Literally, we can’t do anything for unicorn problems.”
Obviously, not every out-of-office is set for a vacation. You also need an out-of-office if you go on an extended business trip or to a conference. But instead of simply telling people you’re at a business event, why not use this opportunity to encourage networking of new business connections?