Vercel makes most of its revenue through its PaaS platform - which supports NextJS first-class, and is their recommend solution for hosting NextJS apps.
By making partner deals with SaaS products like Sitecore, contentful,.... where they become the main SDK for their products, leaving everyone else to DIY their integrations.
So you end up having to use Next.js if not in the mood to use less capable integrations, and then eventually end up deploying the application in Vercel infrastructure.
