> If it turns out that "command X" crashes for you...
As a project maintainer, I hope you recognize that people will run your software on all sorts of hardware and software configurations that don't match how you've tested it. It's impossible for you to test all possible scenarios. Requiring that every potential bug reporter explicitly acknowledge that their issue might be unique to their particular setup in order to assuage your apparently-fragile ego is unreasonable and counter-productive.
If you think the issue is unlikely to be an actual bug, that would seem like the correct course to take. If you suspect it might depend on other details and you're keen to investigate more, you could ask for more details.
One related thing that many projects do is to have a bug template that asks for details such as software versions, operating system, CPU, etc. This can help a lot in reproducing bugs.
Depends how you want your project to be perceived.
If you don't give a crap, and just want to close issues then sure. ;)
If you're interested in finding out why the bug is occurring in such a strange way, and potentially solving the problem... then working with the user to figure out the cause (whether it's their fault or not) is going to be more useful. :)
If you're the only maintainer of your project though, and it happens a lot then personally I'm not sure what the right approach is.
The projects I'm involved with do have it happen, but it's not that often. So we're not too burned out by those things.