The power surge from turning machines off and on is only a factor for cheesy electronics. Good electronics are built for that, just as they're built assuming that a device might be on indefinitely.
All good hardware can run all the time without issues. In some cases, hard drive bearing life is longer when the machine is run continuously. Sitting on a shelf can be more damaging for old drives than running.
Aside from leaky capacitors and fans, old hardware, especially Mac hardware, should be able to run indefinitely. I have two VAXstation machines from the early 1990s which have probably been on for at least fifteen of the last twenty years, plus an Amiga 1200 which has been on since 1995 with short exceptions. That's how it's supposed to work. My PowerMac 9600 server hasn't been rebooted since it was moved to the new datacenter nearly a year ago, and part of that can be attributed to the fact that the hardware is overengineered, good quality hardware. PC makers generally tend to try to save money, so there's generally not as much quality.
All good hardware can run all the time without issues. In some cases, hard drive bearing life is longer when the machine is run continuously. Sitting on a shelf can be more damaging for old drives than running.
Aside from leaky capacitors and fans, old hardware, especially Mac hardware, should be able to run indefinitely. I have two VAXstation machines from the early 1990s which have probably been on for at least fifteen of the last twenty years, plus an Amiga 1200 which has been on since 1995 with short exceptions. That's how it's supposed to work. My PowerMac 9600 server hasn't been rebooted since it was moved to the new datacenter nearly a year ago, and part of that can be attributed to the fact that the hardware is overengineered, good quality hardware. PC makers generally tend to try to save money, so there's generally not as much quality.