There are quite a number of systems out there that offer "backend services" for your mobile app (i.e. Parse, etc.) - many of these have free tiers of service, making it easy to get started, and after some level of usage you have to move to a "paid" level as your volume grows.
For many developers, these systems are going to be the easiest way to get your app connected with API services.
However, for some developers, maintaining and running your own system provides the best means to secure and safe guard your users data against a large companies need to "monetize" your data (i.e. selling your user's usage data to advertising companies, etc.) - after all, it costs these companies money to offer a "free tier" - and they will try to recoup this cost wherever they can.
With Proxima, not only do you get powerful API services, but you also get a complete FRONT END website with over 100+ different modules to help you run your business. If you go with one of the big "backend as a service" companies, you are on your own when it comes to creating the website you need to sell your product.
We know Proxima is not going to be for everyone - that allows us to focus on our core set of users and make sure it is perfect for their use case.