After being used to Visual Studio, where the project and solution files are not a 1-1 match to the file system, I used Eclipse (or some other Java IDE) and found to my shock that when I remove files from the project it also deletes them from disk.

Not as bad as this but certainly an eye-opener.

Totally the guy's fault. No one in their right mind should have 3 months (or even a few days) worth of code without a backup/version control system set up.

It's his fault for not having a backup, yes.

It is not his fault that the tool deleted thousands of files.

Don't confuse yourself; the tool did a bad thing, and so did the user, and those are two, separate, bad things.

The user is not to blame for the tool's nearly cavalier deletion of 5000 files, and the tool is not to blame for the user's failure to have a recovery method.

Solution:

1) Reproduce exact problem. 2) Say "Fascinating" in your best Spock impression. 3) Restore from daily backup.

If you cannot do 3, then you've found THE base problem.

the tool doing something unexpected is one problem.

the user failing to prepare for disaster is another.

don't blame tool problems on the user. blame the user's problem on the user. blame the tool's problems on the tool.

There are two root problems. One is the user's failure to set up a recovery solution, the other is the tool's cavalier ability to delete 5000 with very little warning.