Another nice thing about RSpec/Capybara is that these tests are framework agnostic. As long as your application has a DOM (or in the case of ReactJS, a virtual DOM), you can write tests against it. So, theoretically, you can swap out your application architecture and your integration (or end-to-end) specs should pass.
I’ve been criticised in the past for writing RSpec/Capybara tests against AngularJS because that’s not the way the AngularJS community like to write integration tests. Same for EmberJS apps. But developers have to learn a new test framework for every different application and often these frameworks are not as mature as RSpec, Capybara, Cucumber, etc.
I understand this application already has acceptance tests in QUnit and I’m not criticising the excellent work that’s been put into this project. I just wondered what the reasoning was and possibly I did not fully comprehend how this application works.