They have the enterprise partners that make Next.js the only officially supported SDK on their SaaS integrations.

See Sitecore Cloud, Sanity, Contentful,....

Really the enterprise partner supports next, but not vanilla js sounds stupid? Honestly I expect them to prioritize nextjs and react given the popularity, but still be open to vanilla js.

I checked sitecore cloud to have special integration for nextjs and reactjs. But it also support vanilla js as well.

Are there really anyone who is exclusive to nextjs?

	▲	pjmlp 7 hours ago \| parent [-]
		Vanilla JS is "supported" if you write the missing parts, e.g. layout service, visual editing integration,... In many places they will say it is supported, but when you look into the details only React/Next.js work out of the box without additional work. A bit like you can deploy Next.js on Vercel, or do it yourself somewhere else.