How is this good practice in Perl?

I'm genuinely asking this. I have found some good practices for me, like for example that every if block should also have an else block, even if that block just dies, because in the long run, I will need code in that block anyway. But I don't see what bugs closing a file prevents or what diagnostics it helps to create. I neglect checking the result of close(), but that's about the only "benefit" I see.