A purpose built application if built well will not only do the job more efficiently but also be easy to maintain. If you write exclusively attached to a framework it creates just as much work for someone who knows the underlying technologies but not the framework as it would for someone who knows a framework. You'll end up tying your application to that framework. Sure, say you want to quickly hire 20 coders to work on a project - use a framework (or be like Facebook, or Google and create your own...). I've found hiring framework developers is a good path to getting work only in that framework. Devs who are more versed in the underlying technologies have in my experience been more flexible and put out better products for the domain they're working in.