It is mostly the extra dependencies needed; javascript runtime (NodeJS), yarn, etc. In my apps, I usually add mini_racer or the_ruby_racer to the Gemfile for handling the JS Runtime so I don't have to worry about machine dependencies. However, with Webpack, you would need it on there. Again, it's not a huge deal, but I would want a reason to add it in. Since their documentation does have a way to support Stimulus without a build system, this would be the route I would go with unless I was doing some other major kind of refactor where the introduction of a build system would benefit. https://github.com/stimulusjs/stimulus/blob/master/INSTALLING.md#using-without-a-build-system