Most business have daily downtime where the entire business is closed as in not business hours. Being sensitive to downtime is more common for companies that has some kind of online service as their primary product, but most companies are not online companies, or even global companies with offices across all the time zones.

Even for online business some downtime might be acceptable or even preferred. I used to work for a company that made most of it's money through a website and it would take the site offline for 8 hours a few weeks before important events to run a full scale load test on the production infrastructure.

Another place I worked we had to schedule downtime even when updating applications that were designed for zero downtime.

I have never worked a place that didn't allow for downtime or even heard of such a place other than the big tech companies.