Seems they can't just sandbox it.

Aren’t most files used on an operating system day to day downloaded from the Internet? This feels like it completely kills that feature’s utility.

>For example, if you accidentally download a malicious file, and it contains links, File Explorer would try to preview it, and it’ll also follow links inside the file as part of the process.

Huh, is this true? Seems like a major risk and entirely unexpected (OTOH it's Microsoft so doing insecure stuff is unsurprising)