I’d side-eye if an OOO for a couple of days off said that, unless someone was in an unusually time-sensitive role. But if someone’s out for long enough that there’s an alternate contact provided, that’s long enough for them not to be wading through missed emails when they get back.
There’s a grim, apologetic vibe to these messages — I’m sorry I’m taking time for myself but I’ll try to check in on occasion! They’re a vivid reflection of a work culture that valorizes constant productivity and the near-total overlap of work and life. But they’re also do a terrible job of what they’re intended to do, e.g., set realistic expectations for both sender and recipient. A vague OOO message traps both parties in an uncomfortable liminal space where both productivity and rest go to die. The original sender is left unsure if they’ll be getting a timely response or a whether the email will go ignored for a time or forever. The original recipient has taken what is a rock solid excuse (time off) and cheapened it, offering a backdoor for email guilt to creep in.

Hi, I will be out of the office starting [MM/DD] through [MM/DD]. If you need immediate assistance during my absence, please contact [name] at [email] or [phone]. I will respond to your emails as soon as possible upon my return on [MM/DD].
The answer lies in writing an effective out-of-office message to help reduce the interruptions. “Let key people know you’ll be gone before you leave,” says Ivan Misner, founder of the global business network BNI and author of Who’s In Your Room? The Secret to Creating Your Best Life. “That will help reduce your email. Then craft an out-of-office message for everyone else.”