The reason why you build from scratch using a framework like Rails, Next, Django, Phoenix or w.e is you build an understanding of your application while building your application. You know how the piece fit together so when a problem comes up or you need to build a new feature you have a full understanding of the application and know how to remove pieces and add pieces to fit the future of the application.
Most of these things aren't even hard to build into you application. The hardest probably being stripe because of webhooks and dealing with the company.
Don't be the hare.