Nothing that high level. Different systems are running independently, some may be redundant to each other in case one fails. But run something long enough especially in extreme conditions and things can drift from the baselines. If a power off and on regularly prevents that it's a lot easier than trying to chase down gremlins that could be different each time they pop up for different reasons.

Even NASA I believe has done such resets from Apollo through the unmanned probes from time to time. Mentioning Windows, the newest versions don't really do this baseline reset if you just shut them down, even if you disable the hibernate/sleep modes, while a restart does.