Some defaults are not good for servers. For example, systemd gives up after a few tries to restart a service. This is really annoying for server administrators when they don’t know about the bad defaults.
If a service fails to startup after n times, I most certainly want to take a look at it as it might as well just end up corrupting its state even more - I don't think it's a fair assumption that most errors will just go away on their own. Nonetheless, it can be configured declaratively as a single line, and as you mention, the default can be changed.
apologies, this gave me pause for a split second but I didn't double check — see sibling comment, I think the captions weren't properly updated by the site reporting the stats.
It doesn't have to be the same exact drive. Mixing drives from different manufacturers (with the same capacity) is often used to prevent correlated failure. ZFS is not using the whole disk, so different disks can be mixed, because the disk often have varying capacity.
