> why don't browsers just include the most popular fonts, so the underlying OS doesn't matter?
Well, pontificating here:
1. Because many applications don't ship with additional fonts, and it's an additional layer of complexity. Some do—Microsoft Word comes to mind, IIRC.
2. Because you're still left with the same problem: unless all browsers can agree on an additional set of standard fonts, you as a web developer will only want to use those installed by Chrome and Edge and Safari and Firefox.
3. Because licensing for desktop application may (?) be more of a pain than licensing for web usage. Which may not matter for Google Fonts, since they may be the license holder for all anyway. I don't know.
Well, pontificating here:
1. Because many applications don't ship with additional fonts, and it's an additional layer of complexity. Some do—Microsoft Word comes to mind, IIRC.
2. Because you're still left with the same problem: unless all browsers can agree on an additional set of standard fonts, you as a web developer will only want to use those installed by Chrome and Edge and Safari and Firefox.
3. Because licensing for desktop application may (?) be more of a pain than licensing for web usage. Which may not matter for Google Fonts, since they may be the license holder for all anyway. I don't know.