I don't think it's laziness. My conscious brain knows that it's anachronistic, but I still have the instinct to use a CDN for the shared caching between sites. Obviously, browser privacy changes mean that isn't a valid reason any more, but for me the instinct is still there.

Sites will setup a CDN to serve their own custom assets, but fonts? nope not doable. It's 100% laziness.

I'm not talking about setting up a CDN for custom assets, I'm talking about using something like jsdelivr or Google Fonts. Back in the day using those was a "best practice" because most people would (in theory) already have whatever font/library you're using cached. A lot of people, myself included, still have that as a habit that takes conscious effort to avoid falling into.