I think I could happily live with say half a dozen fonts on the web (plus variations of bold/italic, if we want to count those as multipliers) for the rest of my life. Sarif, SansSarif, Mono, Weird - that's really my ability or care to tell fonts apart, when I'm there for the interesting article or funny video.
But it's that tension:
I, as a consumer, am happy with simplicity
They, as producers, want branding and differentiation (not to mention tracking and all sorts of other things)
Ultimately, and we mustn't forget this, they the producers are the ones investing effort they need a return on; and we the consumers are lousy when it comes to voting with our feet, dollars, scrolling thumbs and back buttons.
We're talking about system fonts here, not webfonts, so they can differentiate as much as they like with webfonts. Webfonts would still be available. Although they'd also have to go into the per-site cache to prevent sites from fingerprinting by whether or not you already had the font loaded via some other site.
(Web fonts can be quite space-effective, if the site can serve a trimmed-down version that doesn't have the whole unicode space in them. CSS even has support for breaking the font into pieces so if a bit of unicode does slip through on some page you can still go get "the rest" of the font.)
But it's that tension:
I, as a consumer, am happy with simplicity
They, as producers, want branding and differentiation (not to mention tracking and all sorts of other things)
Ultimately, and we mustn't forget this, they the producers are the ones investing effort they need a return on; and we the consumers are lousy when it comes to voting with our feet, dollars, scrolling thumbs and back buttons.