I get both sides of this argument. Some businesses have certain periods where it’s extremely busy followed by an ebb in work. Accountants for example may be balls-to-the-wall at year end, but that period doesn’t justify hiring somebody who might otherwise have their thumb up their ass and nothing to do most of the rest of the year. I’ve also had IT jobs that resolved around projects in this way., and there are always a certain number of SME’s that you kinda need at launch.

At the other side, I’ve known employers who basically ran the bare-minimum amount of staff for a team/project (or less and worked the rest to the bone) and getting them to sign off on holidays for any reasonable length of time was near impossible. Those are the types that would try to call you from the middle of open-heart-surgery if they could, and yeah anyone in this situations should be looking for a new job. The hard part being that getting the time to do proper job hunting was often also similarly difficult because of work, and bills still needed to be paid.