They weren’t saying that’s the entirety of their message, just that that’s the phrase they’re using instead of ‘out of office’
There are a million reasons why people feel the need to sheepishly telegraph that they’ll be checking email while OOO: a toxic workplace culture; a set of bad managers who don’t model work/life balance or use manipulative tactics like saying, ‘feel free to take some time if you need it’; companies that are so focused on lean growth they don’t have anyone to pick up the slack when an employee opts to take time off. These days, merely having the confidence to step away from your job by taking the vacation time granted to you in the terms of your employment agreement is still a privilege in the American workforce.

Don't be afraid to use a pop cultural reference that the audience would recognize. Instead of bemoaning your absence, they'll have something fun and familiar to laugh at.
Different companies have different holiday policies. If you're going to be out of office during the holidays, state it in your email. Hello, Thank you for your email! Season's greetings. I can't to your email now as the office is closed for the holidays. I will not be checking my email from December 22 through January 4. If there's an emergency, please contact me at 123-456-7890. Otherwise, I'll respond to your email as soon as possible when I return. Thank you, Jim Parker. 8. Temporary Out-of-Office Email for Attending a Conference If you're going to a business conference, state it out in your out of office email. This type of email is also a great way to show your contacts that you're growing and advancing your job. Hello, Thank you for reaching out! I am out of office attending the National Association of Sale Manager’s conference in Houston, Texas. I'll be checking my emails occasionally, in case of an emergency, please contact my team member, John Doe at [email protected] or 123-456-7890 Regards, Dorian Emmanuel. 9. Out-of-Office with a Promotion