I agree also,

I did lose files after crashes but in the early 90s on HP-UX 8, or Linux 0.99... can't remember after with JFS...

As Neo mentions, its not the OS crash the vulnerability but more the Human intervention on those files been modified e.g I saw Sun servers after a reboot where no one could connect, because someone modified the passwd file NOT using vi... and many more similar cases, so for peace of mind I always make a copy I modify and once done add .ori to the original so whatever I can compare... My remarks apply mostly to any Unix configuration files except sudoers need editing with vi ( as depending on the state of the machine is the only editor working...)

It is true that modern editors as Neo described have funky functionalities that are more than simple cosmetics and would be a pity not to use, but also as he adds: with caution..

What I wanted to mention was more: In a panic mode you tend to forget a lot of things like when a system crashes, you may well have a mail ( but who looks at his mbox?) from the system saying you were editing a file and the system saved the state of the file under the name XXXXXXX, you open them with vi -rdepending the content and how bad the crash you may find the system managed to leave the original in his precedent state ( so before editing or last save ) and have in XXXXXX the last state of current modifications of the file, it may not be complete but at least you haven't lost all, and most important it avoided your system some unwanted file corruption... this may be the reason of with JFS no one can remember losing anything these last 25 years...

But it's not a reason for not being careful when doing sysadmin tasks