A face shield would be better than failing to create a makeshift covering from a shirt for most people and it'd be resistant to decomposing so it could be stored long term in a home. It'd be a reasonable thing to stockpile.
[0] https://www.cdc.gov/coronavirus/2019-ncov/prevent-getting-si...
I also can’t imagine a situation where you can order and wait for a shield but don’t have the time or resources to get a surgical mask or cloth.
And obviously the shield alone isn’t going to protect you from particles. And it might not help slow the spread if you’re infected yourself.
But again I’m speculating. If the health professionals say they need them and the public doesn’t, I’ll defer to them. I’m not an expert in their field and I don’t want to pretend to be or cause anyone to think I am.
So many people on HN and in tech have the same attitude that if they just spend 5 minutes thinking about something then they can intuit an answer and that they must be right. This is a dangerous way of thinking. If anyone took what you’ve been saying as correct they’d be endangering themselves and depriving medical professionals of tools they need.