Yes. Charles is a perfectly valid go-to solution for all problems solved by proxy, too. But Proxy aims to be more user friendly – Charles GUI is a bit messy and outdated.

The core of Proxy are it's filters and modifiers. Filters give you the ability to select specific requests/response pairs from the list of all of them, and modifiers make it possible to change the behavior and data a request/response pair carries. Modifiers are implemented in only a few lines and the idea was that they could be done in almost any language (read: ruby and other lightweight stuff), so the low-memory footprint along with simple, extensible filters would make a powerful developer tool – or the most configurable ad blocker that there is.