In just looking for a definitive answer really, on a modern system does doing a hard shutdown via the power button cause any hardware or software damage ?
Sometimes you have no choice where you have to shutdown via the power button, obviously power cuts can do similar.
You can certainly corrupt your file system or files. If you're really unlucky, you can corrupt something critical that might prevent your OS from booting. For instance you might break a RAID1 array and lose all your data or trash a drive's boot sector.
Hardware-wise it's a lot less likely, but you are potentially powering off hard drives that haven't had a chance to park their heads, though nowadays drives are pretty resilient to that sort of thing that would potentially damage hardware from a decade ago.
The only other proviso is that there are some occasions that could be catastrophic, such as losing power in the middle of a BIOS upgrade, that could render the hardware effectively dead. Most motherboard manufacturers have ways of recovering from that, and I've even seen similar system on Asus routers. I wouldn't like to try and fix a hard drive that had the power pulled in the middle of a firmware upgrade.
So in short, a hard reset is never recommended unless absolutely necessary. On a modern system there are too many other things going on in the background, being cached in memory, or being written down to storage without you knowing about it.
If you find you're doing it a lot because of system lockups or somesuch, you're best off finding the cause and fixing that, because sooner or later it will cause you a problem of one sort of another.
