If you need a Windows admin that states proficiency in Wnidows in the CV, you can infer that not much attention has been put on the CV. If not much attention has been put in the much important first contact with your company, what’s the experience going to be n months down the line, with e.g. powershell scripts that don’t come with spellchecking?

Mostly, hiring has a biased risk matrix. You don’t get hurt by missing a good candidate so much as hiring a bad one. So that makes you conservative in choices. Obviously 1 typo can happen but think about 5 to 10. If you have a lot of CVs to wade through, awful documents going to the bin is not a bad first step in the process.