There are many ways that marketing companies describe the concept of losing track of a visitor after they have payed for them to visit a Landing Page or Proxy.
"Breaking Proxy", "Lead Leakage", "Losing Attribution", etc
The purpose of creating a Proxy is so you can drive inbound traffic to a copy of a customer's existing website, but be able to track all leads that are generated within that campaign via Call Tracking and Form Fill capture.
But if a Visitor to the Proxy clicks on any link that takes them outside the Proxy, you immediately lose the ability to track what they do after that. This could be any sort of link (Instagram, a Press Article on their local news station, or linking to their Yelp Profile). You can't reasonably stop the Visitor from visiting these links without affecting the User Experience.
But there are cases where you want to make sure you have a deep enough "net" or “gates” to keep the Visitor tracked as much as possible during their Session.
The Devhub Proxy solution gives you full flexibility to decide what paths you want the Visitor to take.