Because you don't always know what kind of content you'll be displaying. Especially if you allow user-generated content. Here's an example I found a few years

Because you don't always know what kind of content you'll be displaying. Especially if you allow user-generated content. Here's an example I found a few years ago - https://shkspr.mobi/blog/2015/11/premature-subsetting-of-web-fonts/ https://shkspr.mobi/blog/2015/11/premature-subsetting-of-web... - an English language website never expected their authors to use the é (e-acute) character. So they removed it from their webfont.