The one major thing I like about Vue is that I can use it to build widgets in an otherwise serverside app without having a JavaScript build step. All I do is link Vue directly and server-side include files containing the template and code for each component.

It is possible, but not a good option, to also use React without a build step by either skipping JSX (ugly and cumbersome to use) or by using the Babel runtime (large, not really meant for production).