Note how many HNers are making the same remark.
Now it doesn't really impact build time and Railway offers Next.js hosting.
Anyway, my point is that no one is forced to use NextJS and if they like NextJS but not Vercel they can always fork it or, apparently write an adapter.
You get to pick Vercel + headless CMS + assets managed + eshop, and you're done in terms of big corporations.
Might seem a lot in licenses, however it allows for smaller dev teams, which is what management floor cares about, all those salaries.