People just like React and the idea of decoupling frontend and backend ( Pretty sure just a few percentage of users use Nextjs with api routes and just use it as Create-React-App with SSG and SSR capabilities ). I haven't used Vercel that much in production but what does it bring compared to Heroku or cheaper and open source self hosted alternatives like Dokku or even caprover with it's really good UI and can deploy any backend as long as it's Dockerizable ?