There's an important second-order benefit to this though:
Companies are forced to ensure that their business works without key personnel for weeks at a time. It forces the company to really think about what situations are emergencies where you have to disturb key personnel on their vacation, and which ones you can actually handle anyway.
In contrast in the US, a common office-politics anti-pattern is that individuals make themselves indispensable to the business, as a form of employment protection. This is ultimately bad for the company, because people quit, people change jobs, and then the business is threatened every time such an individual quits.
When every employee is gone for weeks at a time every year, it gives the company opportunity to identify weak spots like this and work around them. And this pays off whenever key personnel leaves their job, for whatever reason.