Here in the grim darkness of the future, every install of a general-purpose OS better be shipping with at least one font (or collection of fonts that operate via glyph fallback) to cover every Unicode codepoint for every language that isn't extinct yet. (In other words, apps that expect to be used with any arbitrary language, including browsers, should not be forced to ship with a font just to ensure basic coverage).
And then, once you have that system-provided codepoint coverage, you can make your font parametric in order to avoid needing to ship multiple copies of the font for different styles. It's not a perfect solution, but it's still pretty acceptable given the constraints.
To provide fonts for N different scripts would multiply the file size by roughly N, and there are a lot of scripts in common use:
https://en.wikipedia.org/wiki/List_of_writing_systems#/media...
Variable fonts would help, but I don't think it would be enough, especially if the goal is to provide a wide selection of fonts.
Even just focusing on Latin scripts, a few hundred fonts would roughly double the compressed download size for browsers and Electron apps.
It might be possible to come up with a better compression scheme which exploits redundancy between different typefaces, but as far as I know, that tech doesn't exist yet.