Indeed. My A7ii uses a very similar sensor to some Nikon cameras, and the sensor is literally always on, because the camera lacks an optical viewfinder. While the noise for very long exposures is negatively affected by the temperature of the sensor if left on too long without being allowed to cool down, the camera is made for having the sensor on for hours and hours every day without issue, and the Nikon sensors aren't any different.

Whats most likely to break, however, is the shutter mechanism. But even that isn't affected here.

My D90 purchased in Europe kind of disagrees with you.