Actually a server should have a UPS which would make it rather safe to use, wouldn't it?
no, because there could be failed PSU, a prolonged power outage, actually a powerloss due to ANY failure of ANY hardware is a problem.
See, the problem with a server is that the drive LIES to the OS in order to gain its speed... it tells the OS "it has been written" when it is just in the ram and has NOT, in fact, been written.
This means you WILL have dataloss even if your software is smart enough to know better... A bank, or any other important database, cannot afford such lies... as long as it KNOWS there is dataloss at a power loss (because the drive did not lie to it), then it can prevent dataloss via redundancy and distributed server platforms... but if the drive lies to it then it thinks it was written and discards that data forever / doesn't bother fixing it.
This is a problem with spindle drive cache as well, which is why they either disable it (server drives allow it to be disabled, or don't even have it in the first place)
With home user software it doesn't matter, we don't have software that can pick up from where it was and avoid damage in case of a power loss, thus, any file we worked on is lost in a power loss, capacitor or no capacitor. So its not useful for a home user...
Another issue btw, is that if 1 single bit of data is corrupt it will FAIL to rebuild (it will literally abort halfway with an error message, part of why classic RAID sucks so bad and needs to be replaced with smarter implementations like zfs's raidz)... anyways, if you have multiple drives, and they lie about what was written (due to cache), then it WILL cause data mismatch, which will fail your raid rebuild in case of a drive replacement (for any reason). Again, the solution is to disable cache... and that is done for spindle drives as well.